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fix #97, we need the RF95 IRQ to be level triggered, or we have slim chance of missing events

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geeksville 2020-04-18 08:48:03 -07:00
parent 4ce7df295e
commit 78470ed3f5
1 changed files with 14 additions and 14 deletions
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28
src/rf95/RH_RF95.cpp
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@ -115,11 +115,11 @@ bool RH_RF95::init()
}
_deviceForInterrupt[_myInterruptIndex] = this;
if (_myInterruptIndex == 0)
attachInterrupt(interruptNumber, isr0, RISING);
attachInterrupt(interruptNumber, isr0, ONHIGH);
else if (_myInterruptIndex == 1)
attachInterrupt(interruptNumber, isr1, RISING);
attachInterrupt(interruptNumber, isr1, ONHIGH);
else if (_myInterruptIndex == 2)
attachInterrupt(interruptNumber, isr2, RISING);
attachInterrupt(interruptNumber, isr2, ONHIGH);
else
return false; // Too many devices, not enough interrupt vectors
@ -153,6 +153,17 @@ void RH_RF95::handleInterrupt()
// Read the interrupt register
uint8_t irq_flags = spiRead(RH_RF95_REG_12_IRQ_FLAGS);
// ack all interrupts, note - we did this already in the RX_DONE case above, and we don't want to do it twice
// Sigh: on some processors, for some unknown reason, doing this only once does not actually
// clear the radio's interrupt flag. So we do it twice. Why? (kevinh - I think the root cause we want level
// triggered interrupts here - not edge. Because edge allows us to miss handling secondard interrupts that occurred
// while this ISR was running. Better to instead, configure the interrupts as level triggered and clear pending
// at the _beginning_ of the ISR. If any interrupts occur while handling the ISR, the signal will remain asserted and
// our ISR will be reinvoked to handle that case)
// kevinh: turn this off until root cause is known, because it can cause missed interrupts!
// spiWrite(RH_RF95_REG_12_IRQ_FLAGS, 0xff); // Clear all IRQ flags
spiWrite(RH_RF95_REG_12_IRQ_FLAGS, 0xff); // Clear all IRQ flags
// Note: there can be substantial latency between ISR assertion and this function being run, therefore
// multiple flags might be set. Handle them all
@ -170,8 +181,6 @@ void RH_RF95::handleInterrupt()
// in the header. If not it might be a stray (noise) packet.*
uint8_t crc_present = spiRead(RH_RF95_REG_1C_HOP_CHANNEL) & RH_RF95_RX_PAYLOAD_CRC_IS_ON;
spiWrite(RH_RF95_REG_12_IRQ_FLAGS, 0xff); // Clear all IRQ flags, required before reading fifo (according to datasheet)
if (!crc_present) {
_rxBad++;
clearRxBuf();
@ -218,15 +227,6 @@ void RH_RF95::handleInterrupt()
_cad = irq_flags & RH_RF95_CAD_DETECTED;
setModeIdle();
}
// ack all interrupts, note - we did this already in the RX_DONE case above, and we don't want to do it twice
if (!(irq_flags & RH_RF95_RX_DONE)) {
// Sigh: on some processors, for some unknown reason, doing this only once does not actually
// clear the radio's interrupt flag. So we do it twice. Why?
// kevinh: turn this off until root cause is known, because it can cause missed interrupts!
// spiWrite(RH_RF95_REG_12_IRQ_FLAGS, 0xff); // Clear all IRQ flags
spiWrite(RH_RF95_REG_12_IRQ_FLAGS, 0xff); // Clear all IRQ flags
}
}
// These are low level functions that call the interrupt handler for the correct