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77 lines
2.1 KiB
Markdown
77 lines
2.1 KiB
Markdown
| Supported Targets | ESP32-S2 | ESP32-S3 |
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| ----------------- | -------- | -------- |
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# ULP RISC-V I2C Example
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This example demonstrates how to use the RTC I2C peripheral from the ULP RISC-V coprocessor in deep sleep.
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The ULP program is based on the BMP180 Temperature and Pressure sensor (https://cz.mouser.com/datasheet/2/783/BST-BMP180-DS000-1509579.pdf) which has an I2C interface. The main CPU initializes the RTC I2C peripheral, the BMP180 sensor and loads the ULP program. It then goes into deep sleep.
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The ULP program periodically measures the temperature and pressure values from the BMP180 sensor and wakesup the main CPU when the values are above a certain thershold.
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### Hardware Required
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* A development board with a SOC which has a RISC-V ULP coprocessor (e.g., ESP32-S2 Saola)
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* A BMP180 sensor module
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* A USB cable for power supply and programming
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## Example output
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Below is the output from this example.
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```
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Not a ULP-RISC V wakeup (cause = 0)
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Initializing RTC I2C ...
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RTC_I2C_STATUS_REG = 0x00000000
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Reading calibration data from BMP180 ...
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ac1 = 7819
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ac2 = -1152
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ac3 = -14317
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ac4 = 34252
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ac5 = 25122
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ac6 = 14289
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b1 = 6515
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b2 = 44
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mb = -32768
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mc = -11786
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md = 2746
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Reading initial uncompensated temperature and pressure data ...
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Uncompensated Temperature = 22865
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Uncompensated Pressure = 41768
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Real Temperature = 24.900000 deg celcius
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Real Pressure = 990.640000 hPa
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Entering in deep sleep
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ESP-ROM:esp32s2-rc4-20191025
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Build:Oct 25 2019
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rst:0x5 (DSLEEP),boot:0x9 (SPI_FAST_FLASH_BOOT)
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SPIWP:0xee
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mode:DIO, clock div:1
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load:0x3ffe6108,len:0x1298
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load:0x4004c000,len:0x92c
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load:0x40050000,len:0x2f04
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entry 0x4004c154
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W (76) spi_flash: Detected size(4096k) larger than the size in the binary image header(2048k). Using the size in the binary image header.
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ULP RISC-V woke up the main CPU
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Uncompensated Temperature = 22865
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Uncompensated Pressure = 41765
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Reading calibration data from BMP180 ...
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ac1 = 7819
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ac2 = -1152
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ac3 = -14317
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ac4 = 34252
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ac5 = 25122
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ac6 = 14289
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b1 = 6515
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b2 = 44
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mb = -32768
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mc = -11786
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md = 2746
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New Real Temperature = 24.900000 deg celcius
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New Real Pressure = 990.550000 hPa
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Entering in deep sleep
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```
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