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Add optional RTS + CTS support to UART #257

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Merged
cmaglie merged 4 commits into from
Nov 29, 2017
Merged

Add optional RTS + CTS support to UART #257

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190cf5d
Add optional RTS + CTS support to UART
sandeepmistry Aug 31, 2017
bd5a7a5
Leverage SERCOM h/w functionality for RTS and CTS
sandeepmistry Aug 31, 2017
c611821
Make UART RTS + CTS configurable in constructor only
sandeepmistry Aug 31, 2017
5344161
Use port manipulation instead of SERCOM h/w for UART RTS
sandeepmistry Sep 1, 2017
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52 changes: 48 additions & 4 deletions cores/arduino/Uart.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -20,13 +20,24 @@
#include "Arduino.h"
#include "wiring_private.h"

Uart::Uart(SERCOM *_s, uint8_t _pinRX, uint8_t _pinTX, SercomRXPad _padRX, SercomUartTXPad _padTX)
#define NO_RTS_PIN 255
#define NO_CTS_PIN 255
#define RTS_RX_THRESHOLD 10

Uart::Uart(SERCOM *_s, uint8_t _pinRX, uint8_t _pinTX, SercomRXPad _padRX, SercomUartTXPad _padTX) :
Uart(_s, _pinRX, _pinTX, _padRX, _padTX, NO_RTS_PIN, NO_CTS_PIN)
{
}

Uart::Uart(SERCOM *_s, uint8_t _pinRX, uint8_t _pinTX, SercomRXPad _padRX, SercomUartTXPad _padTX, uint8_t _pinRTS, uint8_t _pinCTS)
{
sercom = _s;
uc_pinRX = _pinRX;
uc_pinTX = _pinTX;
uc_padRX=_padRX ;
uc_padTX=_padTX;
uc_padRX = _padRX ;
uc_padTX = _padTX;
uc_pinRTS = _pinRTS;
uc_pinCTS = _pinCTS;
}

void Uart::begin(unsigned long baudrate)
Expand All @@ -39,6 +50,23 @@ void Uart::begin(unsigned long baudrate, uint16_t config)
pinPeripheral(uc_pinRX, g_APinDescription[uc_pinRX].ulPinType);
pinPeripheral(uc_pinTX, g_APinDescription[uc_pinTX].ulPinType);

if (uc_padTX == UART_TX_RTS_CTS_PAD_0_2_3) {
if (uc_pinCTS != NO_CTS_PIN) {
pinPeripheral(uc_pinCTS, g_APinDescription[uc_pinCTS].ulPinType);
}
}

if (uc_pinRTS != NO_RTS_PIN) {
pinMode(uc_pinRTS, OUTPUT);

EPortType rtsPort = g_APinDescription[uc_pinRTS].ulPort;
pul_outsetRTS = &PORT->Group[rtsPort].OUTSET.reg;
pul_outclrRTS = &PORT->Group[rtsPort].OUTCLR.reg;
ul_pinMaskRTS = (1ul << g_APinDescription[uc_pinRTS].ulPin);

*pul_outclrRTS = ul_pinMaskRTS;
}

sercom->initUART(UART_INT_CLOCK, SAMPLE_RATE_x16, baudrate);
sercom->initFrame(extractCharSize(config), LSB_FIRST, extractParity(config), extractNbStopBit(config));
sercom->initPads(uc_padTX, uc_padRX);
Expand All @@ -64,6 +92,13 @@ void Uart::IrqHandler()
{
if (sercom->availableDataUART()) {
rxBuffer.store_char(sercom->readDataUART());

if (uc_pinRTS != NO_RTS_PIN) {
// RX buffer space is below the threshold, de-assert RTS
if (rxBuffer.availableForStore() < RTS_RX_THRESHOLD) {
*pul_outsetRTS = ul_pinMaskRTS;
}
}
}

if (sercom->isDataRegisterEmptyUART()) {
Expand Down Expand Up @@ -102,7 +137,16 @@ int Uart::peek()

int Uart::read()
{
return rxBuffer.read_char();
int c = rxBuffer.read_char();

if (uc_pinRTS != NO_RTS_PIN) {
// if there is enough space in the RX buffer, assert RTS
if (rxBuffer.availableForStore() > RTS_RX_THRESHOLD) {
*pul_outclrRTS = ul_pinMaskRTS;
}
}

return c;
}

size_t Uart::write(const uint8_t data)
Expand Down
6 changes: 6 additions & 0 deletions cores/arduino/Uart.h
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@ class Uart : public HardwareSerial
{
public:
Uart(SERCOM *_s, uint8_t _pinRX, uint8_t _pinTX, SercomRXPad _padRX, SercomUartTXPad _padTX);
Uart(SERCOM *_s, uint8_t _pinRX, uint8_t _pinTX, SercomRXPad _padRX, SercomUartTXPad _padTX, uint8_t _pinRTS, uint8_t _pinCTS);
void begin(unsigned long baudRate);
void begin(unsigned long baudrate, uint16_t config);
void end();
Expand All @@ -52,6 +53,11 @@ class Uart : public HardwareSerial
uint8_t uc_pinTX;
SercomRXPad uc_padRX;
SercomUartTXPad uc_padTX;
uint8_t uc_pinRTS;
volatile uint32_t* pul_outsetRTS;
volatile uint32_t* pul_outclrRTS;
uint32_t ul_pinMaskRTS;
uint8_t uc_pinCTS;

SercomNumberStopBit extractNbStopBit(uint16_t config);
SercomUartCharSize extractCharSize(uint16_t config);
Expand Down