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Added comments and fixed a bug in codec's source

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ISO15693 codec was undocumented and without comments in relevant parts. I decided to spend 3 days diving into XMega interrupts and Chameleon's lowest level code. Now, I hope, it should be more readable for everyone, even newbies like my old self was before I started this deep dive.

Also, I fixed the bug referenced here https://github.com/geo-rg/ChameleonMini/issues/4 which locked the chameleon when no response was to be sent to the reader
This commit is contained in:
Federico Cerutti
2018-12-26 19:51:30 +01:00
parent e92b3588e0
commit 9a0ee807aa
1 changed files with 121 additions and 33 deletions
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Firmware/Chameleon-Mini/Codec/ISO15693.c
+121 -33
View File
@@ -3,6 +3,7 @@
*
* Created on: 25.01.2017
* Author: Phillip Nash
* Modified by: ceres-c
*/
#include "ISO15693.h"
@@ -81,19 +82,33 @@ static volatile uint16_t ReadCommandFromReader = 0;
#ifdef CONFIG_VICINITY_SUPPORT
// Started when a single pulse has been detected
// ISR(CODEC_DEMOD_IN_INT0_VECT)
/* This function implements CODEC_DEMOD_IN_INT0_VECT interrupt vector.
* It is called when a pulse is detected in CODEC_DEMOD_IN_PORT (PORTB).
* The relevatn interrupt vector is registered to CODEC_DEMOD_IN_MASK0 (PIN1) via:
* CODEC_DEMOD_IN_PORT.INT0MASK = CODEC_DEMOD_IN_MASK0;
* and unregistered writing the INT0MASK to 0
*/
// ISR(CODEC_DEMOD_IN_INT0_VECT)
void isr_ISO15693_CODEC_DEMOD_IN_INT0_VECT(void)
{
// Start sample timer
/* Start sample timer CODEC_TIMER_SAMPLING (TCD0).
* Set Counter Channel C (CCC) with relevant bitmask (TC0_CCCIF_bm),
* the period for clock sampling is specified in StartISO15693Demod.
*/
CODEC_TIMER_SAMPLING.INTFLAGS = TC0_CCCIF_bm;
/* Sets register INTCTRLB to TC_CCCINTLVL_HI_gc = (0x03<<4) to enable compare/capture for high level interrupts on Channel C (CCC) */
CODEC_TIMER_SAMPLING.INTCTRLB = TC_CCCINTLVL_HI_gc;
/* Disable this interrupt */
/* Disable this interrupt as we've already sensed the relevant pulse and will use our internal clock from now on */
CODEC_DEMOD_IN_PORT.INT0MASK = 0;
}
/* This function is called from isr_ISO15693_CODEC_TIMER_SAMPLING_CCC_VECT
* when we have 8 bits in SampleRegister and they represent an end of frame.
*/
INLINE void ISO15693_EOC(void)
{
/* Set bitrate required by the reader on SOF for our following response */
BitRate1 = 256 * 4; // 256 * 4 - 1
if (CodecBuffer[0] & ISO15693_REQ_DATARATE_HIGH)
BitRate1 = 256;
@@ -107,18 +122,35 @@ INLINE void ISO15693_EOC(void)
BitRate2 = BitRate1;
}
CODEC_TIMER_LOADMOD.CTRLD = 0;
CODEC_TIMER_LOADMOD.INTFLAGS = TC0_CCBIF_bm;
/* Disable event action for CODEC_TIMER_LOADMOD (TCE0) as we're done receiving data */
CODEC_TIMER_LOADMOD.CTRLD = TC_EVACT_OFF_gc;
/* Set Counter Channel B (CCB) with relevant bitmask (TC0_CCBIF_bm), the period for clock sampling is specified below */
CODEC_TIMER_LOADMOD.INTFLAGS = TC0_CCBIF_bm; // TODO This might not be needed since commenting it does not break anything
/* Sets register INTCTRLB to TC_CCBINTLVL_HI_gc = (0x03<<2) to enable compare/capture for high level interrupts on channel B */
CODEC_TIMER_LOADMOD.INTCTRLB = TC_CCBINTLVL_HI_gc;
/* Set the period for CODEC_TIMER_LOADMOD (TCE0) to Bitrate - 1 because PERBUF is 0-based
*
* TODO Why are we using PERBUF instead of PER?
* With PERBUF the period register will occur on the next overflow.
*/
CODEC_TIMER_LOADMOD.PERBUF = BitRate1 - 1;
Flags.DemodFinished = 1;
/* Sets timer off for CODEC_TIMER_SAMPLING (TCD0) disabling clock source */
CODEC_TIMER_SAMPLING.CTRLA = TC_CLKSEL_OFF_gc;
/* Sets register INTCTRLB to 0 to disable all compare/capture interrupts */
CODEC_TIMER_SAMPLING.INTCTRLB = 0;
}
/* This function is registered to CODEC_TIMER_SAMPLING (TCD0)'s Counter Channel C (CCC).
* When the timer is enabled, this is called on counter's overflow
*
* It demodulates bits received from the reader and saves them in CodecBuffer.
*
* It disables its own interrupt when receives an EOF (calling ISO15693_EOC) or when it receives garbage
*/
// ISR(CODEC_TIMER_SAMPLING_CCC_VECT) // Reading data sent from the reader
void isr_ISO15693_CODEC_TIMER_SAMPLING_CCC_VECT(void)
void isr_ISO15693_CODEC_TIMER_SAMPLING_CCC_VECT(void)
{
/* Shift demod data */
SampleRegister = (SampleRegister << 1) | (!(CODEC_DEMOD_IN_PORT.IN & CODEC_DEMOD_IN_MASK) ? 0x01 : 0x00);
@@ -137,9 +169,11 @@ void isr_ISO15693_CODEC_TIMER_SAMPLING_CCC_VECT(void)
} else if (SampleRegister == SOC_1_OF_256_CODE) {
DemodState = DEMOD_1_OUT_OF_256_STATE;
SampleDataCount = 0;
} else { // No SOC. Restart and try again
} else { // No SOC. Restart and try again, we probably received garbage.
Flags.DemodFinished = 1;
/* Sets timer off for CODEC_TIMER_SAMPLING (TCD0) disabling clock source */
CODEC_TIMER_SAMPLING.CTRLA = TC_CLKSEL_OFF_gc;
/* Sets register INTCTRLB to 0 to disable all compare/capture interrupts */
CODEC_TIMER_SAMPLING.INTCTRLB = 0;
}
break;
@@ -230,21 +264,28 @@ void isr_ISO15693_CODEC_TIMER_SAMPLING_CCC_VECT(void)
}
/* This function is registered to CODEC_TIMER_LOADMOD (TCE0)'s Counter Channel B (CCB).
* When the timer is enabled, this is called on counter's overflow
*
* It modulates the carrier with consuming bytes in CodecBuffer until ByteCount is 0.
*
* It disables its own interrupt when all data has been sent
*/
//ISR(CODEC_TIMER_LOADMOD_CCB_VECT)
void isr_ISO15693_CODEC_TIMER_LOADMOD_CCB_VECT(void)
{
static void* JumpTable[] = {
[LOADMOD_START_SINGLE] = &&LOADMOD_START_SINGLE_LABEL,
[LOADMOD_SOF_SINGLE] = &&LOADMOD_SOF_SINGLE_LABEL,
[LOADMOD_BIT0_SINGLE] = &&LOADMOD_BIT0_SINGLE_LABEL,
[LOADMOD_BIT1_SINGLE] = &&LOADMOD_BIT1_SINGLE_LABEL,
[LOADMOD_EOF_SINGLE] = &&LOADMOD_EOF_SINGLE_LABEL,
[LOADMOD_START_DUAL] = &&LOADMOD_START_DUAL_LABEL,
[LOADMOD_SOF_DUAL] = &&LOADMOD_SOF_DUAL_LABEL,
[LOADMOD_BIT0_DUAL] = &&LOADMOD_BIT0_DUAL_LABEL,
[LOADMOD_BIT1_DUAL] = &&LOADMOD_BIT1_DUAL_LABEL,
[LOADMOD_EOF_DUAL] = &&LOADMOD_EOF_DUAL_LABEL,
[LOADMOD_FINISHED] = &&LOADMOD_FINISHED_LABEL
[LOADMOD_START_SINGLE] = &&LOADMOD_START_SINGLE_LABEL,
[LOADMOD_SOF_SINGLE] = &&LOADMOD_SOF_SINGLE_LABEL,
[LOADMOD_BIT0_SINGLE] = &&LOADMOD_BIT0_SINGLE_LABEL,
[LOADMOD_BIT1_SINGLE] = &&LOADMOD_BIT1_SINGLE_LABEL,
[LOADMOD_EOF_SINGLE] = &&LOADMOD_EOF_SINGLE_LABEL,
[LOADMOD_START_DUAL] = &&LOADMOD_START_DUAL_LABEL,
[LOADMOD_SOF_DUAL] = &&LOADMOD_SOF_DUAL_LABEL,
[LOADMOD_BIT0_DUAL] = &&LOADMOD_BIT0_DUAL_LABEL,
[LOADMOD_BIT1_DUAL] = &&LOADMOD_BIT1_DUAL_LABEL,
[LOADMOD_EOF_DUAL] = &&LOADMOD_EOF_DUAL_LABEL,
[LOADMOD_FINISHED] = &&LOADMOD_FINISHED_LABEL
};
if ( (StateRegister >= LOADMOD_START_SINGLE) && (StateRegister <= LOADMOD_FINISHED) ) {
@@ -255,7 +296,7 @@ void isr_ISO15693_CODEC_TIMER_LOADMOD_CCB_VECT(void)
LOADMOD_START_SINGLE_LABEL:
/* Application produced data. With this interrupt we are aligned to the bit-grid. */
ShiftRegister = SOF_PATTERN;
ShiftRegister = SOF_PATTERN;
BitSent = 0;
/* Fallthrough */
LOADMOD_SOF_SINGLE_LABEL:
@@ -425,22 +466,25 @@ void isr_ISO15693_CODEC_TIMER_LOADMOD_CCB_VECT(void)
return;
LOADMOD_FINISHED_LABEL:
/* Sets timer off for CODEC_TIMER_LOADMOD (TCE0) disabling clock source as we're done modulating */
CODEC_TIMER_LOADMOD.CTRLA = TC_CLKSEL_OFF_gc;
/* Sets register INTCTRLB to 0 to disable all compare/capture interrupts */
CODEC_TIMER_LOADMOD.INTCTRLB = 0;
CodecSetSubcarrier(CODEC_SUBCARRIERMOD_OFF, SUBCARRIER_1);
CodecSetSubcarrier(CODEC_SUBCARRIERMOD_OFF, 0);
Flags.LoadmodFinished = 1;
return;
}
#endif /* CONFIG_VICINITY_SUPPORT */
/* This functions resets all global variables used in the codec and enables interrupts to wait for reader data */
void StartISO15693Demod(void) {
/* Reset global variables to default values */
CodecBufferPtr = CodecBuffer;
Flags.DemodFinished = 0;
Flags.LoadmodFinished = 0;
DemodState = DEMOD_SOC_STATE;
LoadModState = LOADMOD_WAIT;
StateRegister = LOADMOD_WAIT;
DataRegister = 0;
SampleRegister = 0;
BitSampleCount = 0;
@@ -453,31 +497,66 @@ void StartISO15693Demod(void) {
CodecSetDemodPower(true);
/* Configure sampling-timer free running and sync to first modulation-pause. */
/* Resets the counter to 0 */
CODEC_TIMER_SAMPLING.CNT = 0;
CODEC_TIMER_SAMPLING.PER = ISO15693_SAMPLE_PERIOD - 1;
CODEC_TIMER_SAMPLING.CCC = ISO15693_SAMPLE_PERIOD / 2 - 14 - 1; /* Half bit. ISR compensate*/
/* Set the period for CODEC_TIMER_SAMPLING (TCD0) to ISO15693_SAMPLE_PERIOD - 1 because PER is 0-based */
CODEC_TIMER_SAMPLING.PER = ISO15693_SAMPLE_PERIOD - 1;
/* Set Counter Channel C (CCC) register with half bit period - 1. (- 14 to compensate ISR timing overhead) */
CODEC_TIMER_SAMPLING.CCC = ISO15693_SAMPLE_PERIOD / 2 - 14 - 1;
/* Set timer for CODEC_TIMER_SAMPLING (TCD0) to ISO15693_SAMPLE_CLK = TC_CLKSEL_DIV2_gc = System Clock / 2
*
* TODO Why system clock / 2 and not iso period?
*/
CODEC_TIMER_SAMPLING.CTRLA = ISO15693_SAMPLE_CLK;
/* Set event action for CODEC_TIMER_SAMPLING (TCD0) to restart and trigger CODEC_TIMER_MODSTART_EVSEL = TC_EVSEL_CH0_gc = Event Channel 0 */
CODEC_TIMER_SAMPLING.CTRLD = TC_EVACT_RESTART_gc | CODEC_TIMER_MODSTART_EVSEL;
/* Set Counter Channel C (CCC) with relevant bitmask (TC0_CCCIF_bm), the period for clock sampling is specified above */
CODEC_TIMER_SAMPLING.INTFLAGS = TC0_CCCIF_bm;
/* Sets register INTCTRLB to TC_CCCINTLVL_OFF_gc = (0x00<<4) to disable compare/capture C interrupts
*
* TODO Why turn it off?
*/
CODEC_TIMER_SAMPLING.INTCTRLB = TC_CCCINTLVL_OFF_gc;
/* Set event action for CODEC_TIMER_LOADMOD (TCE0) to restart and trigger CODEC_TIMER_MODSTART_EVSEL = TC_EVSEL_CH0_gc = Event Channel 0 */
CODEC_TIMER_LOADMOD.CTRLD = TC_EVACT_RESTART_gc | CODEC_TIMER_MODSTART_EVSEL;
CODEC_TIMER_LOADMOD.PER = 4192 + 128 + 128 - 1;
/* Set the period for CODEC_TIMER_LOADMOD (TCE0) to... some magic numbers?
* Using PER instead of PERBUF breaks it when receiving ISO15693_APP_NO_RESPONSE from Application.
*
* TODO What are these numbers?
*/
CODEC_TIMER_LOADMOD.PERBUF = 4192 + 128 + 128 - 1;
/* Sets register INTCTRLA to 0 to disable timer error or overflow interrupts */
CODEC_TIMER_LOADMOD.INTCTRLA = 0;
/* Sets register INTCTRLB to 0 to disable all compare/capture interrupts */
CODEC_TIMER_LOADMOD.INTCTRLB = 0;
/* Set timer for CODEC_TIMER_SAMPLING (TCD0) to TC_CLKSEL_EVCH6_gc = Event Channel 6 */
CODEC_TIMER_LOADMOD.CTRLA = TC_CLKSEL_EVCH6_gc;
/* Start looking out for modulation pause via interrupt. */
CODEC_DEMOD_IN_PORT.INTFLAGS = 0x03;
/* Sets register INTFLAGS to PORT_INT0LVL_HI_gc = (0x03<<0) to enable compare/capture for high level interrupts on CODEC_DEMOD_IN_PORT (PORTB) */
CODEC_DEMOD_IN_PORT.INTFLAGS = PORT_INT0LVL_HI_gc;
/* Sets INT0MASK to CODEC_DEMOD_IN_MASK0 = PIN1_bm to use it as source for port interrupt 0 */
CODEC_DEMOD_IN_PORT.INT0MASK = CODEC_DEMOD_IN_MASK0;
}
void ISO15693CodecInit(void)
{
CodecInitCommon();
/* Register isr_ISO15693_CODEC_TIMER_SAMPLING_CCC_VECT function
* to CODEC_TIMER_SAMPLING (TCD0)'s Counter Channel C (CCC)
*/
isr_func_TCD0_CCC_vect = &isr_ISO15693_CODEC_TIMER_SAMPLING_CCC_VECT;
/* Register isr_ISO15693_CODEC_DEMOD_IN_INT0_VECT function
* to CODEC_DEMOD_IN_PORT (PORTB) interrupt 0
*/
isr_func_CODEC_DEMOD_IN_INT0_VECT = &isr_ISO15693_CODEC_DEMOD_IN_INT0_VECT;
/* Register isr_ISO15693_CODEC_TIMER_LOADMOD_CCB_VECT function
* to CODEC_TIMER_LOADMOD (TCE0)'s Counter Channel B (CCB)
*/
isr_func_CODEC_TIMER_LOADMOD_CCB_VECT = &isr_ISO15693_CODEC_TIMER_LOADMOD_CCB_VECT;
StartISO15693Demod();
}
@@ -486,11 +565,12 @@ void ISO15693CodecDeInit(void)
/* Gracefully shutdown codec */
CODEC_DEMOD_IN_PORT.INT0MASK = 0;
/* Reset global variables to default values */
CodecBufferPtr = CodecBuffer;
Flags.DemodFinished = 0;
Flags.LoadmodFinished = 0;
DemodState = DEMOD_SOC_STATE;
LoadModState = LOADMOD_WAIT;
StateRegister = LOADMOD_WAIT;
DataRegister = 0;
SampleRegister = 0;
BitSampleCount = 0;
@@ -499,15 +579,22 @@ void ISO15693CodecDeInit(void)
ByteCount = 0;
ShiftRegister = 0;
//Disable sample timer
/* Disable sample timer */
/* Sets timer off for CODEC_TIMER_SAMPLING (TCD0) disabling clock source */
CODEC_TIMER_SAMPLING.CTRLA = TC_CLKSEL_OFF_gc;
/* Disable event action for CODEC_TIMER_SAMPLING (TCD0) */
CODEC_TIMER_SAMPLING.CTRLD = TC_EVACT_OFF_gc;
/* Sets register INTCTRLB to TC_CCCINTLVL_OFF_gc = (0x00<<4) to disable compare/capture C interrupts */
CODEC_TIMER_SAMPLING.INTCTRLB = TC_CCCINTLVL_OFF_gc;
/* Restore Counter Channel C (CCC) interrupt mask (TC0_CCCIF_bm) */
CODEC_TIMER_SAMPLING.INTFLAGS = TC0_CCCIF_bm;
//Disable load modulation
/* Disable load modulation */
/* Disable event action for CODEC_TIMER_LOADMOD (TCE0) */
CODEC_TIMER_LOADMOD.CTRLD = TC_EVACT_OFF_gc;
/* Sets register INTCTRLB to TC_CCBINTLVL_OFF_gc = (0x00<<2) to disable compare/capture B interrupts */
CODEC_TIMER_LOADMOD.INTCTRLB = TC_CCBINTLVL_OFF_gc;
/* Restore Counter Channel B (CCB) interrupt mask (TC0_CCBIF_bm) */
CODEC_TIMER_LOADMOD.INTFLAGS = TC0_CCBIF_bm;
CodecSetSubcarrier(CODEC_SUBCARRIERMOD_OFF, 0);
@@ -554,8 +641,10 @@ void ISO15693CodecTask(void)
}
} else {
/* No data to be processed. Disable T1 waiting and start listening again */
/* No data to process. Disable CODEC_TIMER_LOADMOD (TCE0) counter and start listening again */
/* Sets timer off for CODEC_TIMER_LOADMOD (TCE0) disabling clock source as we're done modulating */
CODEC_TIMER_LOADMOD.CTRLA = TC_CLKSEL_OFF_gc;
/* Sets register INTCTRLB to 0 to disable all compare/capture interrupts */
CODEC_TIMER_LOADMOD.INTCTRLB = 0;
StartISO15693Demod();
@@ -564,8 +653,7 @@ void ISO15693CodecTask(void)
if (Flags.LoadmodFinished) {
Flags.LoadmodFinished = 0;
/* Load modulation has been finished. Stop it and start to listen
* for incoming data again. */
/* Load modulation has been finished. Stop it and start to listen for incoming data again. */
StartISO15693Demod();
}
}