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HardwareSerial::attachRts - new optional parameter to invert signal #765

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HardwareSerial::attachRts - new optional parameter to invert signal #765

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073cb2f
HardwareSerial::attachRts - new optional parameter to invert signal
KurtE Sep 27, 2024
239af37
Changed API as you requested: attachRtsInverted
KurtE Sep 28, 2024
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21 changes: 20 additions & 1 deletion teensy4/HardwareSerial.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -244,11 +244,13 @@ void HardwareSerialIMXRT::begin(uint32_t baud, uint16_t format)

inline void HardwareSerialIMXRT::rts_assert()
{
DIRECT_WRITE_LOW(rts_pin_baseReg_, rts_pin_bitmask_);
if (rts_pin_invert_) DIRECT_WRITE_HIGH(rts_pin_baseReg_, rts_pin_bitmask_);
else DIRECT_WRITE_LOW(rts_pin_baseReg_, rts_pin_bitmask_);
}

inline void HardwareSerialIMXRT::rts_deassert()
{
if (rts_pin_invert_) DIRECT_WRITE_LOW(rts_pin_baseReg_, rts_pin_bitmask_);
DIRECT_WRITE_HIGH(rts_pin_baseReg_, rts_pin_bitmask_);
}

Expand Down Expand Up @@ -365,6 +367,23 @@ bool HardwareSerialIMXRT::attachRts(uint8_t pin)
if (pin < CORE_NUM_DIGITAL) {
rts_pin_baseReg_ = PIN_TO_BASEREG(pin);
rts_pin_bitmask_ = PIN_TO_BITMASK(pin);
rts_pin_invert_ = false;
pinMode(pin, OUTPUT);
rts_assert();
} else {
rts_pin_baseReg_ = NULL;
return 0;
}
return 1;
}

bool HardwareSerialIMXRT::attachRtsInverted(uint8_t pin)
{
if (!(hardware->ccm_register & hardware->ccm_value)) return 0;
if (pin < CORE_NUM_DIGITAL) {
rts_pin_baseReg_ = PIN_TO_BASEREG(pin);
rts_pin_bitmask_ = PIN_TO_BITMASK(pin);
rts_pin_invert_ = true;
pinMode(pin, OUTPUT);
rts_assert();
} else {
Expand Down
8 changes: 7 additions & 1 deletion teensy4/HardwareSerial.h
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Original file line number Diff line number Diff line change
Expand Up @@ -240,7 +240,12 @@ class HardwareSerialIMXRT : public HardwareSerial
// receive more data, or HIGH when the serial device should pause transmission.
// All digital pins are supported.
bool attachRts(uint8_t pin);
// Configure CTS flow control. Teensy will transmit when this pin is LOw
// Same as attachRts except the signal levels are reversed.
// Configure RTS flow control. The pin will be HIGH when Teensy is able to
// receive more data, or LOW when the serial device should pause transmission.
// All digital pins are supported.
bool attachRtsInverted(uint8_t pin);
// Configure CTS flow control. Teensy will transmit when this pin is LOW
// and will pause transmission when the pin is HIGH. Only specific pins are
// supported. See https://www.pjrc.com/teensy/td_uart.html
bool attachCts(uint8_t pin);
Expand Down Expand Up @@ -327,6 +332,7 @@ class HardwareSerialIMXRT : public HardwareSerial

volatile uint32_t *rts_pin_baseReg_ = 0;
uint32_t rts_pin_bitmask_ = 0;
bool rts_pin_invert_ = false;

inline void rts_assert();
inline void rts_deassert();
Expand Down