CANBUS timing question

mikroC, mikroBasic and mikroPascal PRO for Microchip’s 32-bit PIC MCUs
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tsadowski_wn
Posts: 24
Joined: 18 Feb 2019 15:50

CANBUS timing question

#1 Post by tsadowski_wn » 03 Dec 2019 17:10

Hi,

I am using a PIC32MZ at 200Mhz. The CANBUS is happily ticking at 250kbits (4us bit time) with:

CAN2Initialize(1,25,3,3,1,Can_Init_Flags);

However if I try to calculate the timing I don't get the expected result.

PB5DIV = 0x8801 -> PBCLK5 = 100MHz

F_TQ = PBCLK5 / (2*(BRP+1)) = 1.923MHz

F_BAUD = F_TQ / (SyncSeg + PropSeg + PhaseSeg1 + PhaseSeg2)
= 1.923 MHz / (1 + 2 + 4 + 4) = 175kbits

Where am I wrong?

Best Regards,
Torsten
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tsadowski_wn
Posts: 24
Joined: 18 Feb 2019 15:50

Re: CANBUS timing question

#2 Post by tsadowski_wn » 04 Dec 2019 11:03

It seems I misunderstood the CANxInitialize parameters. The parameters are the prescaler and time quanta values and not the corresponding register values, which are off by 1.

Cheers,
Torsten
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