Merge branch 'doc/adc_example_doc_improve' into 'master'

doc(adc): Update README.md file of adc example.

See merge request idf/esp-idf!2665
This commit is contained in:
Wang Jia Lin 2018-12-06 15:22:50 +08:00
commit a36d714d1a
2 changed files with 103 additions and 27 deletions

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# Example: ADC1
# ADC1 Example
This test code shows how to configure ADC1 and read the voltage connected to GPIO pin.
(See the README.md file in the upper level 'examples' directory for more information about examples.)
### ADC1 functions:
This example shows how to configure ADC1 and read the voltage connected to GPIO pin.
ADC1_CHANNEL_6: GPIO34, voltage range [0V..1.1V], the data range [0..4095]
## How to use example
### Test:
### Hardware Required
Please connect the test voltage to GPIO34
* A development board with ESP32 SoC (e.g., ESP32-DevKitC, ESP-WROVER-KIT, etc.)
* A USB cable for power supply and programming
In this example, we use `ADC_UNIT_1` by default, we need to connect a voltage source (0 ~ 3.3v) to GPIO34. If another ADC unit is selected in your application, you need to change the GPIO pin (please refer to Chapter 4.11 of the `ESP32 Technical Reference Manual`).
### Configure the project
```
make menuconfig
```
* Set serial port under Serial Flasher Options.
### Build and Flash
Build the project and flash it to the board, then run monitor tool to view serial output:
```
make -j4 flash monitor
```
(To exit the serial monitor, type ``Ctrl-]``.)
See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.
## Example Output
Running this example, you will see the following log output on the serial monitor:
```
Raw: 486 Voltage: 189mV
Raw: 435 Voltage: 177mV
Raw: 225 Voltage: 128mV
Raw: 18 Voltage: 79mV
```
## Troubleshooting
* program upload failure
* Hardware connection is not correct: run `make monitor`, and reboot your board to see if there are any output logs.
* The baud rate for downloading is too high: lower your baud rate in the `menuconfig` menu, and try again.
For any technical queries, please open an [issue](https://github.com/espressif/esp-idf/issues) on GitHub. We will get back to you soon.

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# Example: ADC2
# ADC2 Example
This test code shows how to configure ADC2 and read the voltage connected to GPIO pin.
(See the README.md file in the upper level 'examples' directory for more information about examples.)
### ADC2 functions:
In this example, we use ADC2 to measure the output of DAC.
ADC1_CHANNEL_7: GPIO27, voltage range [0V..3.1V], the data range [0..4095],
saturates at about 1.1V.
## How to use example
DAC_CHANNEL_1: GPIO25, output range [0V..3.3V]
### Hardware Required
### Test:
* A development board with ESP32 SoC (e.g., ESP32-DevKitC, ESP-WROVER-KIT, etc.)
* A USB cable for power supply and programming
Please choose the channel (GPIO) to output DAC signals and the channel to input
signals to ADC by menuconfig:
make menuconfig
We use ADC1_CHANNEL_7 (GPIO27) and DAC_CHANNEL_1 (GPIO25) by default, you need to short the two GPIOs (if you have changed the ADC2 and DAC channel, please refer to Chapter 4.11 of the `ESP32 Technical Reference Manual` to get the pin number).
Then connect two pins by a wire directly.
### Configure the project
E.g. Choose GPIO27 for ADC and GPIO 25 for DAC in menuconfig (default option).
Then connect them up.
```
make menuconfig
```
Connection of ADC and DAC to the same pin is also allowed. In this case, you don't
have to connect by a wire externally. E.g. choose GPIO 26 for both ADC and DAC in
menuconfig.
* Set serial port under Serial Flasher Options.
* Set ADC2 and DAC channel in "Example Configuration"
### Build and Flash
Build the project and flash it to the board, then run monitor tool to view serial output:
```
make -j4 flash monitor
```
(To exit the serial monitor, type ``Ctrl-]``.)
See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.
## Example Output
Running this example, you will see the following log output on the serial monitor:
```
ADC channel 7 @ GPIO 27, DAC channel 1 @ GPIO 25.
adc2_init...
start conversion.
1: 150
2: 203
3: 250
4: 300
5: 351
6: 400
7: 441
8: 491
9: 547
10: 595
...
```
## Troubleshooting
* program upload failure
* Hardware connection is not correct: run `make monitor`, and reboot your board to see if there are any output logs.
* The baud rate for downloading is too high: lower your baud rate in the `menuconfig` menu, and try again.
For any technical queries, please open an [issue](https://github.com/espressif/esp-idf/issues) on GitHub. We will get back to you soon.