libs/RFID.MFRC522
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Use yield() in busy wait loops

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Also, be more scientific about the timeouts rather than using a set
number of loops, the time of which depends on the value of the
MRFC522_SPICLOCK as well as F_CPU. Instead, use a set number of
milliseconds as a deadline.
This commit is contained in:
Jared Hancock
2021-08-19 21:26:01 -05:00
committed by Rotzbua
parent 8f9c07f84f
commit c553f4df61
1 changed files with 14 additions and 4 deletions
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18
src/MFRC522.cpp
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@@ -167,7 +167,9 @@ MFRC522::StatusCode MFRC522::PCD_CalculateCRC( byte *data, ///< In: Pointer to
// TODO check/modify for other architectures than Arduino Uno 16bit // TODO check/modify for other architectures than Arduino Uno 16bit
// Wait for the CRC calculation to complete. Each iteration of the while-loop takes 17.73us. // Wait for the CRC calculation to complete. Each iteration of the while-loop takes 17.73us.
for (uint16_t i = 5000; i > 0; i--) { uint32_t deadline = millis() + 89;
do {
// DivIrqReg[7..0] bits are: Set2 reserved reserved MfinActIRq reserved CRCIRq reserved reserved // DivIrqReg[7..0] bits are: Set2 reserved reserved MfinActIRq reserved CRCIRq reserved reserved
byte n = PCD_ReadRegister(DivIrqReg); byte n = PCD_ReadRegister(DivIrqReg);
if (n & 0x04) { // CRCIRq bit set - calculation done if (n & 0x04) { // CRCIRq bit set - calculation done
@@ -177,7 +179,10 @@ MFRC522::StatusCode MFRC522::PCD_CalculateCRC( byte *data, ///< In: Pointer to
result[1] = PCD_ReadRegister(CRCResultRegH); result[1] = PCD_ReadRegister(CRCResultRegH);
return STATUS_OK; return STATUS_OK;
} }
yield();
} }
while (millis() < deadline);
// 89ms passed and nothing happend. Communication with the MFRC522 might be down. // 89ms passed and nothing happend. Communication with the MFRC522 might be down.
return STATUS_TIMEOUT; return STATUS_TIMEOUT;
} // End PCD_CalculateCRC() } // End PCD_CalculateCRC()
@@ -422,6 +427,7 @@ void MFRC522::PCD_SoftPowerUp(){
if(!(val & (1<<4))){ // if powerdown bit is 0 if(!(val & (1<<4))){ // if powerdown bit is 0
break;// wake up procedure is finished break;// wake up procedure is finished
} }
yield();
} }
} }
@@ -481,8 +487,9 @@ MFRC522::StatusCode MFRC522::PCD_CommunicateWithPICC( byte command, ///< The co
// In PCD_Init() we set the TAuto flag in TModeReg. This means the timer automatically starts when the PCD stops transmitting. // In PCD_Init() we set the TAuto flag in TModeReg. This means the timer automatically starts when the PCD stops transmitting.
// Each iteration of the do-while-loop takes 17.86μs. // Each iteration of the do-while-loop takes 17.86μs.
// TODO check/modify for other architectures than Arduino Uno 16bit // TODO check/modify for other architectures than Arduino Uno 16bit
uint16_t i; uint32_t deadline = millis() + 36;
for (i = 2000; i > 0; i--) {
do {
byte n = PCD_ReadRegister(ComIrqReg); // ComIrqReg[7..0] bits are: Set1 TxIRq RxIRq IdleIRq HiAlertIRq LoAlertIRq ErrIRq TimerIRq byte n = PCD_ReadRegister(ComIrqReg); // ComIrqReg[7..0] bits are: Set1 TxIRq RxIRq IdleIRq HiAlertIRq LoAlertIRq ErrIRq TimerIRq
if (n & waitIRq) { // One of the interrupts that signal success has been set. if (n & waitIRq) { // One of the interrupts that signal success has been set.
break; break;
@@ -490,9 +497,12 @@ MFRC522::StatusCode MFRC522::PCD_CommunicateWithPICC( byte command, ///< The co
if (n & 0x01) { // Timer interrupt - nothing received in 25ms if (n & 0x01) { // Timer interrupt - nothing received in 25ms
return STATUS_TIMEOUT; return STATUS_TIMEOUT;
} }
yield();
} }
while (millis() < deadline);
// 35.7ms and nothing happend. Communication with the MFRC522 might be down. // 35.7ms and nothing happend. Communication with the MFRC522 might be down.
if (i == 0) { if (millis() >= deadline) {
return STATUS_TIMEOUT; return STATUS_TIMEOUT;
} }