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sdio_slave: rewrite the doc and highlight efuse-burning as the default option for 3.3V modules
This commit is contained in:
Michael (XIAO Xufeng)
parent
51d811a71c
commit
07166a6b18
@ -1,153 +1,268 @@
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SD Pullup Requirements
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SD Pullup Requirements
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======================
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======================
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CMD and DATA lines D0-D3 of the slave should be pulled up by 50KOhm resistor
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CMD and DATA lines D0-D3 of the slave should be pulled up by 10 kOhm resistor
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even in 1-bit mode or SPI mode. The pullups of the slave cards should be
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even in 1-bit mode or SPI mode. The pullups of the slave cards should be
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connected even if they're not connected to the host.
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connected even if they're not connected to the host.
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The MTDI strapping pin is incompatible with DAT2 line pull-up by default
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The MTDI strapping pin by default is incompatible with DAT2 line pullup when
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when the code flash is 3.3V. See :ref:`mtdi_strapping_pin` below.
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the flash is 3.3 V. See :ref:`technical_detail_sdio` below.
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Pullup inside Official Modules
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.. _existing_issues_official_modules_sdio:
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------------------------------
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For Espressif official modules, different weak pullups / pulldowns are
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Possible Issues
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connected to CMD, and DATA pins as below. To use these modules,
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---------------
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these pins are required to be pulled up by 50KOhm resistors, since internal
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weak pullups are insufficient.
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+-----------------------+-----+--------------------------+------+----------------------+------+
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Here is a list of Espressif chips, official modules and development kits and
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| GPIO | 15 | 2 | 4 | 12 | 13 |
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the issues they may have during SDIO development. Since the requirements are
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+=======================+=====+==========================+======+======================+======+
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for the pullups on the SD bus, the issues should be resolved no matter if it
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| Name | CMD | DAT0 | DAT1 | DAT2 | DAT3 |
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is a host or slave. Each issue is linked to its solution. The solution for a
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+-----------------------+-----+--------------------------+------+----------------------+------+
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specific issue may be different for host and slave.
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| At startup | WPU | WPD | WPD | PU for 1.8v flash; | WPU |
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| | | | | WPD for 3.3v flash | |
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+-----------------------+-----+--------------------------+------+----------------------+------+
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| Strapping requirement | | Low to download to flash | | High for 1.8v flash; | |
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| | | | | Low for 3.3v flash | |
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+-----------------------+-----+--------------------------+------+----------------------+------+
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- WPU: Weak pullup
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Official modules are usually without the sufficient pullups on all 6 pins, it
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- WPD: Weak pulldown
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is suggested to select one of the development kits for either host or slave
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- PU: Pullup inside the module
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to provide such pullups.
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For Wrover modules, they use 1.8v flash, and have pullup on GPIO12 inside.
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Chips
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For Wroom-32 Series, PICO-D4 modules, they use 3.3v flash, and is weakly
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^^^^^
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pulled down internally. See :ref:`mtdi_strapping_pin` below.
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Pullup on Official Devkit (WroverKit)
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- ESP32 (except D2WD, see `ESP32 datasheet <https://www.espressif.com/sites/default/files/documentation/esp32_datasheet_en.pdf>`_):
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--------------------------------------
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:ref:`sd_pullup_no_pullups`, whether the strapping conflicts with DAT2 is determined
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by the flash you are using. Please see :ref:`strapping_conflicts_dat2` if
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your flash chip is 3.3 V.
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For official Wrover Kit (till version 3), some of the pullups are provided on
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- ESP32-D2WD:
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the board as the table below. For other devkits that don't have pullups,
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:ref:`sd_pullup_no_pullups`, :ref:`no_pullup_on_gpio12`
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please connect them yourselves.
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+-----------------------+-----+------+------+------+---------+
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- ESP32-PICO-D4:
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| GPIO | 15 | 2 | 4 | 12 | 13 |
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:ref:`sd_pullup_no_pullups`, :ref:`strapping_conflicts_dat2`
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+=======================+=====+======+======+======+=========+
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| Name | CMD | DAT0 | DAT1 | DAT2 | DAT3 |
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+-----------------------+-----+------+------+------+---------+
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| Pullup on the Kit | PU | PU | PU | | PU & PD |
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+-----------------------+-----+------+------+------+---------+
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- PU: Pullup
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Modules
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- PD: Pulldown
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^^^^^^^
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The DAT3 pullup conflicts with JTAG pulldown in WroverKit v3 and earlier, please
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- ESP32-WROOM-32 Series:
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either:
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Including ESP32-WROOM-32, ESP32-WROOM-32D, ESP32-WROOM-32U and
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ESP32-SOLO-1.
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1. pull it up by resistor less than 5KOhm (2kOhm suggested) in 4-bit mode.
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:ref:`sd_pullup_no_pullups`, :ref:`strapping_conflicts_dat2`.
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2. pull it up or drive it high by host or VDD3.3V in 1-bit mode.
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.. _mtdi_strapping_pin:
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- ESP32-WROVER Series:
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Including ESP32-WROVER and ESP32-WROVER-I.
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MTDI strapping pin
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:ref:`sd_pullup_no_pullups`.
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------------------
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MTDI (GPIO12) is used as a bootstrapping pin to select output voltage of an
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- ESP32-WROVER-B Series:
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internal regulator which powers the flash chip (VDD_SDIO). This pin has an
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Including ESP32-WROVER-B and ESP32-WROVER-IB.
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internal pulldown so if left unconnected it will read low at reset (selecting
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default 3.3V operation). When adding a pullup to this pin for SD card
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operation, consider the following:
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- For boards which don't use the internal regulator (VDD_SDIO) to power the
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:ref:`sd_pullup_no_pullups`, :ref:`strapping_conflicts_dat2`.
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flash, GPIO12 can be pulled high.
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- For boards which use 1.8V flash chip, GPIO12 needs to be pulled high at
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reset. This is fully compatible with SD card operation.
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- On boards which use the internal regulator and a 3.3V flash chip, GPIO12
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must be low at reset. This is incompatible with SD card operation. Please
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check the table below to see whether your modules/kits use 3.3v flash.
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+-----------------+---------------+--------------------------------------+
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.. _sdio_dev_kits:
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| Module | Flash voltage | DAT2 connections |
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+=================+===============+======================================+
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| PICO-D4 | 3.3V | Internal PD, change EFUSE and pullup |
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+-----------------+ + or disable DAT2 line* +
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| Wroom-32 Series | | |
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+-----------------+---------------+--------------------------------------+
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| Wrover | 1.8V | Internal PU, pullup suggested |
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+-----------------+---------------+--------------------------------------+
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Official devkits of different types and version mount different types of
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Development Boards
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modules, please refer to the table below to see whether your devkit can
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^^^^^^^^^^^^^^^^^^
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support SDIO slave without steps above.
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+--------------------------+-----------------+---------------+
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- ESP32-PICO-KIT:
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| Devkit | Module | Flash voltage |
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Including PICO-KIT v4.1, v4.0 and v3.
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+==========================+=================+===============+
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| PICO Kit | PICO-D4 | 3.3V |
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+--------------------------+-----------------+ (see steps +
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| DevKitC | Wroom-32 Series | below) |
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+--------------------------+ + +
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| WroverKit v2 and earlier | | |
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+--------------------------+-----------------+---------------+
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| WroverKit v3 | Wrover | 1.8V |
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+--------------------------+-----------------+---------------+
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If your board requires internal regulator with 3.3v output, to make it
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:ref:`sd_pullup_no_pullups`, :ref:`strapping_conflicts_dat2`,
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compatible with SD pullup, you can either:
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:ref:`gpio2_strapping_pin`.
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- **In the case using ESP32 host only**, external pullup can be omitted and an
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- ESP32-DevKitC:
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internal pullup can be enabled using a ``gpio_pullup_en(GPIO_NUM_12);`` call.
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Including ESP32-DevKitC v4 and v2.
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Most SD cards work fine when an internal pullup on GPIO12 line is enabled.
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Note that if ESP32 experiences a power-on reset while the SD card is
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sending data, high level on GPIO12 can be latched into the bootstrapping
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register, and ESP32 will enter a boot loop until external reset with
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correct GPIO12 level is applied.
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- **In the case using ESP32 slave in 1-bit mode**, speicfy
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``SDIO_SLAVE_FLAG_DAT2_DISABLED`` in the slave to avoid slave detecting on
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DAT2 line. Note the host will not know 4-bit mode is not supported any more
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by the standard CCCR register. You have to tell the host use 1-bit only.
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- **For ESP32 host or slave**, another option is to burn the flash voltage
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selection efuses. This will permanently select 3.3V output voltage for the
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internal regulator, and GPIO12 will not be used as a bootstrapping pin.
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Then it is safe to connect a pullup resistor to GPIO12. This option is
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suggested for production use. NOTE this cannot be reverted once the EFUSE
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is burnt.
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The following command can be used to program flash voltage selection efuses **to 3.3V**:
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:ref:`sd_pullup_no_pullups`, :ref:`strapping_conflicts_dat2`,
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:ref:`gpio2_strapping_pin`.
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- ESP-WROVER-KIT:
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v4.1: Have pullups, but :ref:`pullup_conflicts_on_gpio13` ,
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:ref:`strapping_conflicts_dat2`.
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v3: Have pullups, but :ref:`pullup_conflicts_on_gpio13`.
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v2 and v1: Have pullups, but :ref:`pullup_conflicts_on_gpio13`,
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:ref:`strapping_conflicts_dat2`, :ref:`gpio2_strapping_pin`.
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You can tell the version of your ESP23-WROVER-KIT version from the module
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on it: v4.1 are with ESP32-WROVER-B modules, v3 are with ESP32-WROVER
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modules, while v2 and v1 are with ESP32-WROOM-32 modules.
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- ESP32-LyraTD-MSC:
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:ref:`strapping_conflicts_dat2`. Have pullups.
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- ESP32-LyraT:
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Have pullups, but :ref:`pullup_conflicts_on_gpio13`
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Non-Espressif Hosts
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^^^^^^^^^^^^^^^^^^^
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Please make sure that your 3rd party SDIO host has correct pullups for all
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the signals.
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Solutions
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---------
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.. _sd_pullup_no_pullups:
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No Pullups
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^^^^^^^^^^
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When developing on boards without pullups, you can either:
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1. If your host and slave are on seperated boards, you can change one of them
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to a board with pullups. Please see :ref:`sdio_dev_kits` to find Espressif
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official boards with pullups.
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2. Connect external pullups to VDD by yourself. Connect these pins without
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pullups to the VDD through a 10 kOhm resistor.
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.. _pullup_conflicts_on_gpio13:
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Pullup Conflicts on GPIO13
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^^^^^^^^^^^^^^^^^^^^^^^^^^
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The DAT3 of slave may not be properly pulled up. You can either:
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1. Use 1-bit mode, and tie DAT3 of slave to VDD.
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2. Use SPI mode.
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3. Remove the pulldown resistors on GPIO13; or pull it up by resistor less
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than 5 kOhm (2 kOhm suggested); or pull it up or drive it high by host or
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VDD3.3V in 1-bit mode.
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.. _strapping_conflicts_dat2:
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Conflicts Between Bootstrap and SDIO on DAT2
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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The strapping requirements conflict with SDIO protocol. See
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:ref:`mtdi_strapping_pin` for the details of this issue. You can either:
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1. (Recomended) Burn the flash voltage selection eFuses. This will
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permanently select 3.3 V output voltage for the internal regulator, and GPIO12
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will not be used as a bootstrapping pin. Then connect a pullup resistor
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to GPIO12.
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.. warning:: Burning eFuse is irreversible. The issue list above may be
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out of date. Do make sure the module you are burning is using a 3.3 V flash
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according to the information on http://www.espressif.com/. If you burn the
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3.3 V eFuses on an 1.8 V module, the module will get broken.
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Run the command below under your IDF folder:
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::
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components/esptool_py/esptool/espefuse.py set_flash_voltage 3.3V
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components/esptool_py/esptool/espefuse.py set_flash_voltage 3.3V
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This command will burn the `XPD_SDIO_TIEH`, `XPD_SDIO_FORCE`, and
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This command will burn the `XPD_SDIO_TIEH`, `XPD_SDIO_FORCE`, and
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`XPD_SDIO_REG` efuses. With all three burned to value 1, the internal
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`XPD_SDIO_REG` eFuses. With all three burned to value 1, the internal
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VDD_SDIO flash voltage regulator is permanently enabled at 3.3V. See
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VDD_SDIO flash voltage regulator is permanently set to 3.3 V. You will
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the technical reference manual for more details.
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see the following log if the burning succeeds:
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::
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`espefuse.py` has a `--do-not-confirm` option if running from an automated flashing script.
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espefuse.py v2.6
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Connecting....
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GPIO2 Strapping pin
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Enable internal flash voltage regulator (VDD_SDIO) to 3.3 V.
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-------------------
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The following eFuses are burned: XPD_SDIO_FORCE, XPD_SDIO_REG, XPD_SDIO_TIEH.
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This is an irreversible operation.
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Type 'BURN' (all capitals) to continue.
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BURN
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VDD_SDIO setting complete.
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You can also run ``components/esptool_py/esptool/espefuse.py summary`` to
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check the status of the eFuses above.
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`espefuse.py` has a ``--do-not-confirm`` option if running from an
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automated flashing script.
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See the ESP32 Technical Reference Manual for more details.
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2. **When using 1-bit mode or SPI mode**, DAT2 signal is not needed (though it
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still has to be pulled up). If the device works as the host, you can leave
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the DAT2 of host floating, and directly connect DAT2 of slave to VDD; or if
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the device works as the slave, specify ``SDIO_SLAVE_FLAG_DAT2_DISABLED`` in
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the slave app to avoid slave detecting on DAT2 line. Note the host will
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not know that 4-bit mode is not supported any more by the standard CCCR
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register. You have to forbid the host from using 4-bit mode.
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.. _no_pullup_on_gpio12:
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No Pullup on GPIO12
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^^^^^^^^^^^^^^^^^^^
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Your module is compatible with the SDIO protocol. Just connect GPIO12 to the
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VDD through a 10 kOhm resistor.
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.. _gpio2_strapping_pin:
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Auto-program Not Working (minor issue)
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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GPIO2 pin is used as a bootstrapping pin, and should be low to enter UART
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GPIO2 pin is used as a bootstrapping pin, and should be low to enter UART
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download mode. You may find it unable to enter the UART download mode if you
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download mode. You may find it unable to enter the UART download mode if you
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correctly connect the pullup of SD on GPIO2. For WroverKit v3, there are
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correctly connect the pullup of SD on GPIO2.
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dedicated circuits to pulldown the GPIO2 when downloading. For other boards,
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one way to do this is to connect GPIO0 and GPIO2 using a jumper, and then the
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auto-reset circuit on most development boards will pull GPIO2 low along with
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GPIO0, when entering download mode.
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- Some boards have pulldown and/or LED on GPIO2. LED is usually ok, but
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Some official kits pull down GPIO2 when downloading. For other boards, you
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pulldown will interfere with D0 signals and must be removed. Check the
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may try to connect GPIO0 and GPIO2 using a jumper, and then the auto-reset
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schematic of your development board for anything connected to GPIO2.
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circuit on most development boards will pull GPIO2 low along with GPIO0, when
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entering download mode. (Some boards have pulldown and/or LED on GPIO2. LED
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is usually ok, but the pulldown resistor will interfere with D0 signals and
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must be removed. Check the schematic of your development board for anything
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connected to GPIO2.)
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If the above way is not working, please just turn off the other device and
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remove the pullups on GPIO2 when you are programming the slave.
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.. _technical_detail_sdio:
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Technical Details
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-----------------
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.. _mtdi_strapping_pin:
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MTDI Strapping Pin
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^^^^^^^^^^^^^^^^^^
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MTDI (GPIO12) is used as a bootstrapping pin to select output voltage of an
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internal regulator which powers the flash chip (VDD_SDIO). This pin has an
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internal pulldown so if left unconnected it will read low at startup
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(selecting default 3.3 V operation).
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For ESP32-WROVER modules, excluding ESP32-WROVER-B, they use 1.8 V flash, and
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have pullup on GPIO12 inside. For other modules, which use 3.3 V flash, have
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no pullups on GPIO12, and GPIO12 is weakly pulled down internally.
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When adding a pullup to this pin for SD card operation, consider the
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following:
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||||||
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- For boards which don't use the internal regulator (VDD_SDIO) to power the
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flash, GPIO12 can be pulled high.
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- For boards which use 1.8 V flash chip, GPIO12 needs to be pulled high at
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reset. This is fully compatible with SD card operation.
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- On boards which use the internal regulator and a 3.3 V flash chip, GPIO12
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||||||
|
must be low at reset. This is incompatible with SD card operation. Please
|
||||||
|
check :ref:`existing_issues_official_modules_sdio` to see whether your board
|
||||||
|
has this issue, and how to solve it.
|
||||||
|
|
||||||
|
Internal Pullups and Strapping Requirements
|
||||||
|
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||||
|
|
||||||
|
It is never recommended to rely on internal weak pullups for SDIO
|
||||||
|
communications, since internal weak pullups are insufficient. But information
|
||||||
|
of the strapping requirements and internal pullups may be useful. For
|
||||||
|
Espressif official modules, different weak pullups / pulldowns are connected
|
||||||
|
to CMD, and DATA pins as below.
|
||||||
|
|
||||||
|
+-----------------------+-----+--------------------------+------+-----------------------+------+
|
||||||
|
| GPIO | 15 | 2 | 4 | 12 | 13 |
|
||||||
|
+=======================+=====+==========================+======+=======================+======+
|
||||||
|
| Name | CMD | DAT0 | DAT1 | DAT2 | DAT3 |
|
||||||
|
+-----------------------+-----+--------------------------+------+-----------------------+------+
|
||||||
|
| At startup | WPU | WPD | WPD | PU for 1.8 V flash; | WPU |
|
||||||
|
| | | | | WPD for 3.3 V flash | |
|
||||||
|
+-----------------------+-----+--------------------------+------+-----------------------+------+
|
||||||
|
| Strapping requirement | | Low to download to flash | | High for 1.8 V flash; | |
|
||||||
|
| | | | | Low for 3.3 V flash | |
|
||||||
|
+-----------------------+-----+--------------------------+------+-----------------------+------+
|
||||||
|
|
||||||
|
- WPU: Weak pullup
|
||||||
|
- WPD: Weak pulldown
|
||||||
|
- PU: Pullup inside the module
|
||||||
@ -8,42 +8,72 @@ The ESP32 SDIO Card peripherals (Host, Slave) shares two sets of pins as below t
|
|||||||
The first set is usually occupied by SPI0 bus which is responsible for the SPI flash holding the code to run.
|
The first set is usually occupied by SPI0 bus which is responsible for the SPI flash holding the code to run.
|
||||||
This means SDIO slave driver can only runs on the second set of pins while SDIO host is not using it.
|
This means SDIO slave driver can only runs on the second set of pins while SDIO host is not using it.
|
||||||
|
|
||||||
+----------+-------+-------+
|
|
||||||
| Pin Name | Slot1 | Slot2 |
|
|
||||||
+ +-------+-------+
|
|
||||||
| | GPIO Number |
|
|
||||||
+==========+=======+=======+
|
|
||||||
| CLK | 6 | 14 |
|
|
||||||
+----------+-------+-------+
|
|
||||||
| CMD | 11 | 15 |
|
|
||||||
+----------+-------+-------+
|
|
||||||
| DAT0 | 7 | 2 |
|
|
||||||
+----------+-------+-------+
|
|
||||||
| DAT1 | 8 | 4 |
|
|
||||||
+----------+-------+-------+
|
|
||||||
| DAT2 | 9 | 12 |
|
|
||||||
+----------+-------+-------+
|
|
||||||
| DAT3 | 10 | 13 |
|
|
||||||
+----------+-------+-------+
|
|
||||||
|
|
||||||
The SDIO slave can run under 3 modes: SPI, 1-bit SD and 4-bit SD modes, which
|
The SDIO slave can run under 3 modes: SPI, 1-bit SD and 4-bit SD modes, which
|
||||||
is detected automatically by the hardware. According to the SDIO
|
is detected automatically by the hardware. According to the SDIO
|
||||||
specification, CMD and DAT0-3 lines should be pulled up no matter in 1-bit,
|
specification, CMD and DAT0-3 lines should be pulled up no matter in 1-bit,
|
||||||
4-bit or SPI mode. Then the host initialize the slave into SD mode by first
|
4-bit or SPI mode.
|
||||||
sending CMD0 with DAT3 pin high, while initialize the slave into SPI mode by
|
|
||||||
sending CMD0 with CS pin (the same pin as DAT3) low.
|
|
||||||
|
|
||||||
.. note:: CMD and DATA lines D0-D3 of the card should be pulled up by 50KOhm resistor
|
Connections
|
||||||
even in 1-bit mode or SPI mode. Most official devkits don't meet the pullup
|
^^^^^^^^^^^
|
||||||
requirements by default, and there are conflicts on strapping pins as well.
|
|
||||||
Please refer to :doc:`sd_pullup_requirements` to see how to setup your
|
+----------+---------------+-------+-------+
|
||||||
system correctly.
|
| Pin Name | Corresponding | Slot1 | Slot2 |
|
||||||
|
+ + pins in SPI +-------+-------+
|
||||||
|
| | mode | GPIO Number |
|
||||||
|
+==========+===============+=======+=======+
|
||||||
|
| CLK | SCLK | 6 | 14 |
|
||||||
|
+----------+---------------+-------+-------+
|
||||||
|
| CMD | MOSI | 11 | 15 |
|
||||||
|
+----------+---------------+-------+-------+
|
||||||
|
| DAT0 | MISO | 7 | 2 |
|
||||||
|
+----------+---------------+-------+-------+
|
||||||
|
| DAT1 | Interrupt | 8 | 4 |
|
||||||
|
+----------+---------------+-------+-------+
|
||||||
|
| DAT2 | N.C. (pullup) | 9 | 12 |
|
||||||
|
+----------+---------------+-------+-------+
|
||||||
|
| DAT3 | #CS | 10 | 13 |
|
||||||
|
+----------+---------------+-------+-------+
|
||||||
|
|
||||||
|
- 1-bit SD mode: Connect CLK, CMD, DAT0, DAT1 pins and the ground.
|
||||||
|
- 4-bit SD mode: Connect all pins and the ground.
|
||||||
|
- SPI mode: Connect SCLK, MOSI, MISO, Interrupt, #CS pins and the ground.
|
||||||
|
|
||||||
|
.. note:: Please check if CMD and DATA lines D0-D3 of the card are properly
|
||||||
|
pulled up by 10 KOhm resistors. This should be ensured even in 1-bit mode
|
||||||
|
or SPI mode. Most official modules don't offer these pullups internally.
|
||||||
|
If you are using official development boards, check
|
||||||
|
:ref:`existing_issues_official_modules_sdio` to see whether your
|
||||||
|
development boards have such pullups.
|
||||||
|
|
||||||
|
.. note:: Most official modules have conflicts on strapping pins with the
|
||||||
|
SDIO slave function. If you are using a ESP32 module with 3.3 V flash
|
||||||
|
inside, you have to burn the EFUSE when you are developing on the module
|
||||||
|
for the first time. See :ref:`existing_issues_official_modules_sdio` to
|
||||||
|
see how to make your modules compatible with the SDIO.
|
||||||
|
|
||||||
|
Here is a list for modules/kits with 3.3 V flash:
|
||||||
|
|
||||||
|
- Modules: ESP32-PICO-D4, ESP32-WROOM-32 series (including ESP32-SOLO-1),
|
||||||
|
ESP32-WROVER-B and ESP32-WROVER-IB
|
||||||
|
- Kits: ESP32-PICO-KIT, ESP32-DevKitC (till v4), ESP32-WROVER-KIT
|
||||||
|
(v4.1 (also known as ESP32-WROVER-KIT-VB), v2, v1 (also known as DevKitJ
|
||||||
|
v1))
|
||||||
|
|
||||||
|
You can tell the version of your ESP23-WROVER-KIT version from the module
|
||||||
|
on it: v4.1 are with ESP32-WROVER-B modules, v3 are with ESP32-WROVER
|
||||||
|
modules, while v2 and v1 are with ESP32-WROOM-32 modules.
|
||||||
|
|
||||||
|
Refer to :doc:`sd_pullup_requirements` for more technical details of the pullups.
|
||||||
|
|
||||||
.. toctree::
|
.. toctree::
|
||||||
:hidden:
|
:hidden:
|
||||||
|
|
||||||
sd_pullup_requirements
|
sd_pullup_requirements
|
||||||
|
|
||||||
|
The host initialize the slave into SD mode by first sending CMD0 with DAT3
|
||||||
|
pin high, or in SPI mode by sending CMD0 with CS pin (the same pin as DAT3)
|
||||||
|
low.
|
||||||
|
|
||||||
After the initialization, the host can enable the 4-bit SD mode by writing
|
After the initialization, the host can enable the 4-bit SD mode by writing
|
||||||
CCCR register 0x07 by CMD52. All the bus detection process are handled by the
|
CCCR register 0x07 by CMD52. All the bus detection process are handled by the
|
||||||
slave peripheral.
|
slave peripheral.
|
||||||
@ -97,7 +127,7 @@ SDIO initialization process (Sector 3.1.2 of `SDIO Simplified
|
|||||||
Specification <https://www.sdcard.org/downloads/pls/>`_), which is described
|
Specification <https://www.sdcard.org/downloads/pls/>`_), which is described
|
||||||
briefly in :ref:`esp_slave_init`.
|
briefly in :ref:`esp_slave_init`.
|
||||||
|
|
||||||
However, there's an ESP32-specific upper-level communication protocol upon
|
Furthermore, there's an ESP32-specific upper-level communication protocol upon
|
||||||
the CMD52/CMD53 to Func 1. Please refer to :ref:`esp_slave_protocol_layer`,
|
the CMD52/CMD53 to Func 1. Please refer to :ref:`esp_slave_protocol_layer`,
|
||||||
or example :example:`peripherals/sdio` when programming your host.
|
or example :example:`peripherals/sdio` when programming your host.
|
||||||
|
|
||||||
|
|||||||
@ -2,7 +2,7 @@ menu "Example Configuration"
|
|||||||
|
|
||||||
config SDIO_DAT2_DISABLED
|
config SDIO_DAT2_DISABLED
|
||||||
bool "Disable the DAT2 in SDIO slave"
|
bool "Disable the DAT2 in SDIO slave"
|
||||||
default y
|
default n
|
||||||
help
|
help
|
||||||
SDIO slave DAT pin is unfortunately the same pin as MTDI, which
|
SDIO slave DAT pin is unfortunately the same pin as MTDI, which
|
||||||
controls the flash power voltage. For 3.3v flash devkits / modules /
|
controls the flash power voltage. For 3.3v flash devkits / modules /
|
||||||
|
|||||||
Loading…
Reference in New Issue
Block a user