feat(uart): support UART Tx Rx pin swap function #2601
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Hi @fpistm, I'm finishing testing at the moment with different STM32 chips and will report back as soon as I'm done and things are ready to be merged :) |
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@fpistm I've finished testing on multiple ST families Nucleo-64 boards. Code works as intended and is ready for merging! In case you want to test yourself here's my sketch: #include <Arduino.h>
#define __XSTR(a) __STR(a)
#define __STR(a) #a
// #define USE_HALFDUPLEX
// Define serials with normal pins order
// RX TX
HardwareSerial Serial4(PC11, PC10);
#ifdef USE_HALFDUPLEX
// TX
HardwareSerial Serial5(PC12);
#else
// RX TX
HardwareSerial Serial5(PD2, PC12);
#endif
// Send from USB to SerialTx, then via wires to SerialRx and then back to USB
#define SerialTx Serial5
#define SerialRx Serial4
int lastButtonState;
void setup() {
pinMode(USER_BTN, INPUT);
Serial.begin(115200);
if (digitalRead(USER_BTN) == LOW) {
// Button held on startup - enable SerialTx pinswap
#ifdef USE_HALFDUPLEX
SerialTx.setTx(PD2);
SerialTx.setHalfDuplex();
#else
SerialTx.setTx(PD2);
SerialTx.setRx(PC12);
#endif
}
SerialTx.begin(9600);
SerialRx.begin(9600);
Serial.printf("%s: pin swap %s, half duplex %s\r\n", __XSTR(SerialTx),
READ_BIT(SerialTx.getHandle()->Instance->CR2, USART_CR2_SWAP) ? "enabled" : "disabled",
SerialTx.isHalfDuplex() ? "enabled" : "disabled");
Serial.println("How to use:");
Serial.printf("Button released USB->%s->%s->USB\r\n", __XSTR(SerialTx), __XSTR(SerialRx));
Serial.printf("Button pressed USB->%s->%s->USB\r\n", __XSTR(SerialRx), __XSTR(SerialTx));
lastButtonState = digitalRead(USER_BTN);
}
void loop() {
int buttonState = digitalRead(USER_BTN);
if (buttonState) {
// Forward transmission SerialTx->SerialRx
if (!lastButtonState) {
#ifdef USE_HALFDUPLEX
// Just switched, enable half-duplex receiver
SerialTx.enableHalfDuplexRx();
#endif
Serial.printf("\r\nButton released: USB->%s->%s->USB\r\n", __XSTR(SerialTx), __XSTR(SerialRx));
}
if (Serial.available()) { // If anything comes in Serial (USB),
SerialTx.write(Serial.read()); // read it and send it out SerialTx
}
if (SerialRx.available()) { // If anything comes in SerialRx
Serial.write(SerialRx.read()); // read it and send it out Serial (USB)
}
} else {
// Reverse transmission SerialRx->SerialTx
if (lastButtonState) {
#ifdef USE_HALFDUPLEX
// Just switched, enable half-duplex receiver
SerialTx.enableHalfDuplexRx();
#endif
Serial.printf("\r\nButton pressed USB->%s->%s->USB\r\n", __XSTR(SerialRx), __XSTR(SerialTx));
}
if (Serial.available()) { // If anything comes in Serial (USB),
SerialRx.write(Serial.read()); // read it and send it out SerialTx
}
if (SerialTx.available()) { // If anything comes in SerialRx
Serial.write(SerialTx.read()); // read it and send it out Serial (USB)
}
}
lastButtonState = buttonState;
}So I would do the following:
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Hi @fronders, thanks for the PR, will try to review it this week. |
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This enables UART Tx and Rx pin swap function on STM32 families that support it (F0, L0, L4, G0, G4, H7 etc.)
In order to enable pin swap, user just needs to swap the pins either when declaring
HardwareSerialobject:or by using
setTx()andsetRx()methods:If the chip does not support the swap, or the pins are incorrect, the library behaves the same way as before (throws an error for invalid pins).
The cool thing is that it even supports half-duplex mode on the normally Rx pin - the Rx pin is used for transmission and reception then. User can either use
Rx == Txtrick as before or just provide a single pin definitionFixes: #2538
See also: #1418