8b7b5821c7
Add NMEA0183 Parser example to illustrate how to use uart event driver together with esp event library to get GPS information.
73 lines
2.4 KiB
Markdown
73 lines
2.4 KiB
Markdown
# UART Echo Example
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(See the README.md file in the upper level 'examples' directory for more information about examples.)
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This example demonstrates how to utilize UART interfaces of ESP32 by echoing back to the sender any data received on
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UART1.
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## How to use example
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### Hardware Required
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The example can be run on any ESP32 development board connected to a PC with a single USB cable for flashing and
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monitoring. The external interface should have 3.3V outputs. You may use e.g. 3.3V compatible USB-to-Serial dongle.
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### Setup the Hardware
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Connect the external serial interface to the ESP32 board as follows.
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| ESP32 Interface | #define | ESP32 Pin | External UART Pin |
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| --- | --- | --- | --- |
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| Transmit Data (TxD) | ECHO_TEST_TXD | GPIO4 | RxD |
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| Receive Data (RxD) | ECHO_TEST_RXD | GPIO5 | TxD |
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| Ground | n/a | GND | GND |
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Optionally, you can set-up and use a serial interface that has RTS and CTS signals in order to verify that the
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hardware control flow works. Connect the extra signals according to the following table, configure both extra pins in
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the example code by replacing existing `UART_PIN_NO_CHANGE` macros with the appropriate pin numbers and configure
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UART1 driver to use the hardware flow control by setting `.flow_ctrl = UART_HW_FLOWCTRL_CTS_RTS` and adding
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`.rx_flow_ctrl_thresh = 122`.
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| ESP32 Interface | #define | ESP32 Pin | External UART Pin |
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| --- | --- | --- | --- |
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| Request to Send (RTS) | ECHO_TEST_RTS | GPIO18 | CTS |
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| Clear to Send (CTS) | ECHO_TEST_CTS | GPIO19 | RTS |
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### Configure the project
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```
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make menuconfig
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```
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or
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```
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idf.py menuconfig
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```
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* Set serial port under Serial Flasher Options.
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### Build and Flash
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Build the project and flash it to the board, then run monitor tool to view serial output:
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```
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make -j4 flash monitor
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```
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or
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```
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idf.py flash monitor
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```
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(To exit the serial monitor, type ``Ctrl-]``.)
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See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.
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## Example Output
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Type some characters in the terminal connected to the external serial interface. As result you should see echo in the
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terminal which is used for flashing and monitoring. You can verify if the echo indeed comes from ESP32 by
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disconnecting either `TxD` or `RxD` pin: no characters will appear when typing.
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## Troubleshooting
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You are not supposed to see the echo in the terminal which is used for flashing and monitoring, but in the other one
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which is connected to UART1.
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