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HAL_ChibiOS: fixed CANFD timings

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our CANFD timings were resulting in a lot of busoff errors. Here is an
example of master at 1Mbit/5MBit:

Getting @SYS/can0_stats.txt as -
------- Clock Config -------
CAN_CLK_FREQ:   80MHz
Std Timings: bitrate=1000000 presc=7
sjw=0 bs1=7 bs2=0 sample_point=90.00000%
FD Timings:  bitrate=5000000 presc=1
sjw=0 bs1=5 bs2=0 sample_point=90.00000%
------- CAN Interface Stats -------
tx_requests:    2689
tx_rejected:    0
tx_overflow:    443
tx_success:     7
tx_timedout:    2232
tx_abort:       0
rx_received:    18470
rx_overflow:    0
rx_errors:      0
num_busoff_err: 34439
num_events:     18477
ECR:            F8
fdf_rx:         18467
fdf_tx_req:     2182
fdf_tx:         0

here is an example with the new timings:

------- Clock Config -------
CAN_CLK_FREQ:   80MHz
Std Timings: bitrate=1000000 presc=8
sjw=1 bs1=8 bs2=1 sample_point=90.00000%
FD Timings:  bitrate=8000000 presc=2
sjw=3 bs1=8 bs2=3 sample_point=80.00000%
------- CAN Interface Stats -------
tx_requests:    3023
tx_rejected:    0
tx_overflow:    0
tx_success:     3023
tx_timedout:    0
tx_abort:       0
rx_received:    27865
rx_overflow:    0
rx_errors:      0
num_busoff_err: 0
num_events:     30888
ECR:            0
fdf_rx:         27862
fdf_tx_req:     3016
fdf_tx:         3016

I am testing between a CubeOrange and a Pixhawk6X. I tested 1, 2, 4, 5
and 8 MBit (which are the only valid FD bitrates in our parameters)

Many thanks to Kai from Salient Motion for finding this issue and
providing the corrected timing table
This commit is contained in:
Andrew Tridgell 2023-06-20 17:16:06 +10:00
parent 52468f0238
commit 1c8048df8f
2 changed files with 50 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

62
libraries/AP_HAL_ChibiOS/CANFDIface.cpp
View File

@ -190,7 +190,7 @@ void CANIface::handleBusOffInterrupt()
_detected_bus_off = true;
}
bool CANIface::computeTimings(const uint32_t target_bitrate, Timings& out_timings)
bool CANIface::computeTimings(const uint32_t target_bitrate, Timings& out_timings) const
{
if (target_bitrate < 1) {
return false;
@ -316,13 +316,46 @@ bool CANIface::computeTimings(const uint32_t target_bitrate, Timings& out_timing
}
out_timings.sample_point_permill = solution.sample_point_permill;
out_timings.prescaler = uint16_t(prescaler - 1U);
out_timings.sjw = 0; // Which means one
out_timings.bs1 = uint8_t(solution.bs1 - 1);
out_timings.bs2 = uint8_t(solution.bs2 - 1);
out_timings.prescaler = uint16_t(prescaler);
out_timings.sjw = 1;
out_timings.bs1 = uint8_t(solution.bs1);
out_timings.bs2 = uint8_t(solution.bs2);
return true;
}
/*
table driven timings for CANFD
*/
bool CANIface::computeFDTimings(const uint32_t target_bitrate, Timings& out_timings) const
{
static const struct {
uint8_t bitrate_mbaud;
uint8_t prescaler;
uint8_t bs1;
uint8_t bs2;
uint8_t sjw;
uint8_t sample_point_pct;
} CANFD_timings[] {
{ 1, 5, 15, 6, 6, 75},
{ 2, 3, 15, 6, 6, 75},
{ 4, 2, 15, 6, 6, 75},
{ 5, 2, 12, 5, 5, 75},
{ 8, 2, 8, 3, 3, 80},
};
for (const auto &t : CANFD_timings) {
if (t.bitrate_mbaud*1000U*1000U == target_bitrate) {
// out_timings has the register bits, which are the actual value minus 1
out_timings.prescaler = t.prescaler;
out_timings.bs1 = t.bs1;
out_timings.bs2 = t.bs2;
out_timings.sjw = t.sjw;
out_timings.sample_point_permill = t.sample_point_pct*10;
return true;
}
}
return false;
}
int16_t CANIface::send(const AP_HAL::CANFrame& frame, uint64_t tx_deadline,
CanIOFlags flags)
{
@ -666,13 +699,13 @@ bool CANIface::init(const uint32_t bitrate, const uint32_t fdbitrate, const Oper
unsigned(timings.prescaler), unsigned(timings.sjw), unsigned(timings.bs1), unsigned(timings.bs2));
//setup timing register
can_->NBTP = ((timings.sjw << FDCAN_NBTP_NSJW_Pos) |
(timings.bs1 << FDCAN_NBTP_NTSEG1_Pos) |
(timings.bs2 << FDCAN_NBTP_NTSEG2_Pos) |
(timings.prescaler << FDCAN_NBTP_NBRP_Pos));
can_->NBTP = (((timings.sjw-1) << FDCAN_NBTP_NSJW_Pos) |
((timings.bs1-1) << FDCAN_NBTP_NTSEG1_Pos) |
((timings.bs2-1) << FDCAN_NBTP_NTSEG2_Pos) |
((timings.prescaler-1) << FDCAN_NBTP_NBRP_Pos));
if (fdbitrate) {
if (!computeTimings(fdbitrate, fdtimings)) {
if (!computeFDTimings(fdbitrate, fdtimings)) {
can_->CCCR &= ~FDCAN_CCCR_INIT;
uint32_t while_start_ms = AP_HAL::millis();
while ((can_->CCCR & FDCAN_CCCR_INIT) == 1) {
@ -685,9 +718,10 @@ bool CANIface::init(const uint32_t bitrate, const uint32_t fdbitrate, const Oper
_fdbitrate = fdbitrate;
Debug("CANFD Timings: presc=%u bs1=%u bs2=%u\n",
unsigned(fdtimings.prescaler), unsigned(fdtimings.bs1), unsigned(fdtimings.bs2));
can_->DBTP = ((fdtimings.bs1 << FDCAN_DBTP_DTSEG1_Pos) |
(fdtimings.bs2 << FDCAN_DBTP_DTSEG2_Pos) |
(fdtimings.prescaler << FDCAN_DBTP_DBRP_Pos));
can_->DBTP = (((fdtimings.bs1-1) << FDCAN_DBTP_DTSEG1_Pos) |
((fdtimings.bs2-1) << FDCAN_DBTP_DTSEG2_Pos) |
((fdtimings.prescaler-1) << FDCAN_DBTP_DBRP_Pos) |
((fdtimings.sjw-1) << FDCAN_DBTP_DSJW_Pos));
}
//RX Config
@ -1111,7 +1145,7 @@ void CANIface::get_stats(ExpandingString &str)
unsigned(timings.bs2), timings.sample_point_permill/10.0f,
_fdbitrate, unsigned(fdtimings.prescaler),
unsigned(fdtimings.sjw), unsigned(fdtimings.bs1),
unsigned(fdtimings.bs2), timings.sample_point_permill/10.0f,
unsigned(fdtimings.bs2), fdtimings.sample_point_permill/10.0f,
stats.tx_requests,
stats.tx_rejected,
stats.tx_overflow,

3
libraries/AP_HAL_ChibiOS/CANFDIface.h
View File

@ -123,7 +123,8 @@ class ChibiOS::CANIface : public AP_HAL::CANIface
const uint8_t self_index_;
bool computeTimings(uint32_t target_bitrate, Timings& out_timings);
bool computeTimings(uint32_t target_bitrate, Timings& out_timings) const;
bool computeFDTimings(uint32_t target_bitrate, Timings& out_timings) const;
void setupMessageRam(void);