Using a Raspberry Pi Pico, MCP 2515 and Micropython to transmit frames over CAN ·

20 May 2024, 00:00
I'm trying to use a Raspberry Pi Pico and MCP 2515 to transmit frames over CAN. For this I'm using CAN bus Module (B) for Raspberry Pi Pico (https://www.waveshare.com/wiki/Pico-CAN-B) and demo code for micropython from the same page (code below).
#!/usr/bin/env python # -*- coding: utf-8 -*- from machine import Pin,SPI,PWM import time ## Configuration Registers */ CANSTAT = 0x0E CANCTRL = 0x0F BFPCTRL = 0x0C TEC = 0x1C REC = 0x1D CNF3 = 0x28 CNF2 = 0x29 CNF1 = 0x2A CANINTE = 0x2B CANINTF = 0x2C EFLG = 0x2D TXRTSCTRL = 0x0D ## Recieve Filters */ RXF0SIDH = 0x00 RXF0SIDL = 0x01 RXF0EID8 = 0x02 RXF0EID0 = 0x03 RXF1SIDH = 0x04 RXF1SIDL = 0x05 RXF1EID8 = 0x06 RXF1EID0 = 0x07 RXF2SIDH = 0x08 RXF2SIDL = 0x09 RXF2EID8 = 0x0A RXF2EID0 = 0x0B RXF3SIDH = 0x10 RXF3SIDL = 0x11 RXF3EID8 = 0x12 RXF3EID0 = 0x13 RXF4SIDH = 0x14 RXF4SIDL = 0x15 RXF4EID8 = 0x16 RXF4EID0 = 0x17 RXF5SIDH = 0x18 RXF5SIDL = 0x19 RXF5EID8 = 0x1A RXF5EID0 = 0x1B ## Receive Masks */ RXM0SIDH = 0x20 RXM0SIDL = 0x21 RXM0EID8 = 0x22 RXM0EID0 = 0x23 RXM1SIDH = 0x24 RXM1SIDL = 0x25 RXM1EID8 = 0x26 RXM1EID0 = 0x27 ## Tx Buffer 0 */ TXB0CTRL = 0x30 TXB0SIDH = 0x31 TXB0SIDL = 0x32 TXB0EID8 = 0x33 TXB0EID0 = 0x34 TXB0DLC = 0x35 TXB0D0 = 0x36 TXB0D1 = 0x37 TXB0D2 = 0x38 TXB0D3 = 0x39 TXB0D4 = 0x3A TXB0D5 = 0x3B TXB0D6 = 0x3C TXB0D7 = 0x3D ## Tx Buffer 1 */ TXB1CTRL = 0x40 TXB1SIDH = 0x41 TXB1SIDL = 0x42 TXB1EID8 = 0x43 TXB1EID0 = 0x44 TXB1DLC = 0x45 TXB1D0 = 0x46 TXB1D1 = 0x47 TXB1D2 = 0x48 TXB1D3 = 0x49 TXB1D4 = 0x4A TXB1D5 = 0x4B TXB1D6 = 0x4C TXB1D7 = 0x4D ## Tx Buffer 2 */ TXB2CTRL = 0x50 TXB2SIDH = 0x51 TXB2SIDL = 0x52 TXB2EID8 = 0x53 TXB2EID0 = 0x54 TXB2DLC = 0x55 TXB2D0 = 0x56 TXB2D1 = 0x57 TXB2D2 = 0x58 TXB2D3 = 0x59 TXB2D4 = 0x5A TXB2D5 = 0x5B TXB2D6 = 0x5C TXB2D7 = 0x5D # ## Rx Buffer 0 */ RXB0CTRL = 0x60 RXB0SIDH = 0x61 RXB0SIDL = 0x62 RXB0EID8 = 0x63 RXB0EID0 = 0x64 RXB0DLC = 0x65 RXB0D0 = 0x66 RXB0D1 = 0x67 RXB0D2 = 0x68 RXB0D3 = 0x69 RXB0D4 = 0x6A RXB0D5 = 0x6B RXB0D6 = 0x6C RXB0D7 = 0x6D # ## Rx Buffer 1 */ RXB1CTRL = 0x70 RXB1SIDH = 0x71 RXB1SIDL = 0x72 RXB1EID8 = 0x73 RXB1EID0 = 0x74 RXB1DLC = 0x75 RXB1D0 = 0x76 RXB1D1 = 0x77 RXB1D2 = 0x78 RXB1D3 = 0x79 RXB1D4 = 0x7A RXB1D5 = 0x7B RXB1D6 = 0x7C RXB1D7 = 0x7D # ##****************************************************************** # * Bit register masks * # *******************************************************************/ # ## TXBnCTRL */ TXREQ = 0x08 TXP = 0x03 # ## RXBnCTRL */ RXM = 0x60 BUKT = 0x04 # ## CANCTRL */ REQOP = 0xE0 ABAT = 0x10 #define OSM = 0x08 CLKEN = 0x04 CLKPRE = 0x03 # ## CANSTAT */ REQOP = 0xE0 ICOD = 0x0E ## CANINTE */ RX0IE = 0x01 RX1IE = 0x02 TX0IE = 0x04 TX1IE = 0x80 TX2IE = 0x10 ERRIE = 0x20 WAKIE = 0x40 MERRE = 0x80 # ## CANINTF */ RX0IF = 0x01 RX1IF = 0x02 TX0IF = 0x04 TX1IF = 0x80 TX2IF = 0x10 ERRIF = 0x20 WAKIF = 0x40 MERRF = 0x80 # ## BFPCTRL */ B1BFS = 0x20 B0BFS = 0x10 B1BFE = 0x08 B0BFE = 0x04 B1BFM = 0x02 B0BFM = 0x01 # ## CNF1 Masks */ SJW = 0xC0 BRP = 0x3F # ## CNF2 Masks */ BTLMODE = 0x80 SAM = 0x40 PHSEG1 = 0x38 PRSEG = 0x07 # ## CNF3 Masks */ WAKFIL = 0x40 PHSEG2 = 0x07 # ## TXRTSCTRL Masks */ TXB2RTS = 0x04 TXB1RTS = 0x02 TXB0RTS = 0x01 # ##****************************************************************** # * Bit Timing Configuration * # *******************************************************************/ # ## CNF1 */ SJW_1TQ = 0x40 SJW_2TQ = 0x80 SJW_3TQ = 0x90 SJW_4TQ = 0xC0 # ## CNF2 */ BTLMODE_CNF3 = 0x80 BTLMODE_PH1_IPT = 0x00 SMPL_3X = 0x40 SMPL_1X = 0x00 PHSEG1_8TQ = 0x38 PHSEG1_7TQ = 0x30 PHSEG1_6TQ = 0x28 PHSEG1_5TQ = 0x20 PHSEG1_4TQ = 0x18 PHSEG1_3TQ = 0x10 PHSEG1_2TQ = 0x08 PHSEG1_1TQ = 0x00 PRSEG_8TQ = 0x07 PRSEG_7TQ = 0x06 PRSEG_6TQ = 0x05 PRSEG_5TQ = 0x04 PRSEG_4TQ = 0x03 PRSEG_3TQ = 0x02 PRSEG_2TQ = 0x01 PRSEG_1TQ = 0x00 # ## CNF3 */ PHSEG2_8TQ = 0x07 PHSEG2_7TQ = 0x06 PHSEG2_6TQ = 0x05 PHSEG2_5TQ = 0x04 PHSEG2_4TQ = 0x03 PHSEG2_3TQ = 0x02 PHSEG2_2TQ = 0x01 PHSEG2_1TQ = 0x00 SOF_ENABLED = 0x80 WAKFIL_ENABLED =0x40 WAKFIL_DISABLED =0x00 # ##****************************************************************** # * Control/Configuration Registers * # *******************************************************************/ # ## CANINTE */ RX0IE_ENABLED= 0x01 RX0IE_DISABLED =0x00 RX1IE_ENABLED =0x02 RX1IE_DISABLED =0x00 G_RXIE_ENABLED =0x03 G_RXIE_DISABLED =0x00 TX0IE_ENABLED= 0x04 TX0IE_DISABLED =0x00 TX1IE_ENABLED =0x08 TX2IE_DISABLED =0x00 TX2IE_ENABLED =0x10 TX2IE_DISABLED =0x00 G_TXIE_ENABLED =0x1C G_TXIE_DISABLED =0x00 ERRIE_ENABLED= 0x20 ERRIE_DISABLED =0x00 WAKIE_ENABLED= 0x40 WAKIE_DISABLED =0x00 IVRE_ENABLED = 0x80 IVRE_DISABLED= 0x00 # ## CANINTF */ RX0IF_SET = 0x01 RX0IF_RESET = 0x00 RX1IF_SET = 0x02 RX1IF_RESET = 0x00 TX0IF_SET = 0x04 TX0IF_RESET = 0x00 TX1IF_SET = 0x08 TX2IF_RESET = 0x00 TX2IF_SET = 0x10 TX2IF_RESET = 0x00 ERRIF_SET = 0x20 ERRIF_RESET = 0x00 WAKIF_SET = 0x40 WAKIF_RESET = 0x00 IVRF_SET = 0x80 IVRF_RESET = 0x00 # ## CANCTRL */ REQOP_CONFIG = 0x80 REQOP_LISTEN = 0x60 REQOP_LOOPBACK =0x40 REQOP_SLEEP = 0x20 REQOP_NORMAL = 0x00 ABORT = 0x10 OSM_ENABLED = 0x08 CLKOUT_ENABLED =0x04 CLKOUT_DISABLED =0x00 CLKOUT_PRE_8 = 0x03 CLKOUT_PRE_4 = 0x02 CLKOUT_PRE_2 = 0x01 CLKOUT_PRE_1 = 0x00 # ## CANSTAT */ OPMODE_CONFIG= 0x80 OPMODE_LISTEN= 0x60 OPMODE_LOOPBACK =0x40 OPMODE_SLEEP = 0x20 OPMODE_NORMAL= 0x00 # ## RXBnCTRL */ RXM_RCV_ALL = 0x60 RXM_VALID_EXT= 0x40 RXM_VALID_STD= 0x20 RXM_VALID_ALL= 0x00 RXRTR_REMOTE = 0x08 RXRTR_NO_REMOTE =0x00 BUKT_ROLLOVER = 0x04 BUKT_NO_ROLLOVER =0x00 FILHIT0_FLTR_1 =0x01 FILHIT0_FLTR_0 =0x00 FILHIT1_FLTR_5 =0x05 FILHIT1_FLTR_4 =0x04 FILHIT1_FLTR_3 =0x03 FILHIT1_FLTR_2 =0x02 FILHIT1_FLTR_1 =0x01 FILHIT1_FLTR_0 =0x00 # ## TXBnCTRL */ TXREQ_SET = 0x08 TXREQ_CLEAR = 0x00 TXP_HIGHEST = 0x03 TXP_INTER_HIGH =0x02 TXP_INTER_LOW= 0x01 TXP_LOWEST = 0x00 # ##****************************************************************** # * Register Bit Masks * # *******************************************************************/ DLC_0 = 0x00 DLC_1 = 0x01 DLC_2 = 0x02 DLC_3 = 0x03 DLC_4 = 0x04 DLC_5 = 0x05 DLC_6 = 0x06 DLC_7 = 0x07 DLC_8 = 0x08 # ##****************************************************************** # * CAN spi commands * # *******************************************************************/ CAN_RESET = 0xC0 CAN_READ = 0x03 CAN_WRITE = 0x02 CAN_RTS = 0x80 CAN_RTS_TXB0 = 0x81 CAN_RTS_TXB1 = 0x82 CAN_RTS_TXB2 = 0x84 CAN_RD_STATUS= 0xA0 CAN_BIT_MODIFY =0x05 CAN_RX_STATUS= 0xB0 CAN_RD_RX_BUFF =0x90 CAN_LOAD_TX = 0x40 # ##****************************************************************** # * Miscellaneous * # *******************************************************************/ DUMMY_BYTE = 0x00 TXB0 = 0x31 TXB1 = 0x41 TXB2 = 0x51 RXB0 = 0x61 RXB1 = 0x71 EXIDE_SET = 0x08 EXIDE_RESET = 0x00 # #CS PORTAbits.RA2 CAN_RATE = { "5KBPS" : [0xA7, 0XBF, 0x07], "10KBPS" : [0x31, 0XA4, 0X04], "20KBPS" : [0x18, 0XA4, 0x04], "50KBPS" : [0x09, 0XA4, 0x04], "100KBPS" : [0x04, 0x9E, 0x03], "125KBPS" : [0x03, 0x9E, 0x03], "250KBPS" : [0x01, 0x1E, 0x03], "500KBPS" : [0x00, 0x9E, 0x03], "800KBPS" : [0x00, 0x92, 0x02], "1000KBPS": [0x00, 0x82, 0x02], } gRXFlag=0 sRXFlag=0 yRXFlag=0 Com_RecBuff = [0, 0, 0, 0, 0, 0, 0, 0] #8 # data = 0 SPI0_CS1 = 1 SPI0_CS0 = 5 debug = False # debug = True class MCP2515(): def __init__(self): self.spi = SPI(0) self.spi = SPI(0,250000,polarity=0, phase=0,sck=Pin(6),mosi=Pin(7),miso=Pin(4)) self.cs = Pin(SPI0_CS0,Pin.OUT) def ReadByte(self, addr): self.cs(0) self.spi.write(bytearray([CAN_READ])) self.spi.write(bytearray([addr])) res = self.spi.read(1) self.cs(1) return int.from_bytes(res,'big') def WriteByte(self, addr): self.cs(0) self.spi.write(bytearray([addr])) self.cs(1) def WriteBytes(self, addr, data): self.cs(0) self.spi.write(bytearray([CAN_WRITE])) self.spi.write(bytearray([addr])) self.spi.write(bytearray([data])) self.cs(1) def Reset(self): self.cs(0) self.spi.write(bytearray([CAN_RESET])) #Reset 0XC0 self.cs(1) def Init(self, speed="125KBPS"): print("Reset") self.Reset() time.sleep(0.1) #set baud rate 125Kbps #<7:6>SJW=00(1TQ) #<5:0>BRP=0x03 (TQ=[2*(BRP+1)]/Fsoc=2*4/8M=1us) #<5:0>BRP=0x03 (TQ=[2*(BRP+1)]/Fsoc=2*8/16M=1us) # self.WriteBytes(CNF1, 7) # self.WriteBytes(CNF2,0x80|PHSEG1_3TQ|PRSEG_1TQ) # self.WriteBytes(CNF3,PHSEG2_3TQ) self.WriteBytes(CNF1, CAN_RATE[speed][0]) self.WriteBytes(CNF2, CAN_RATE[speed][1]) self.WriteBytes(CNF3, CAN_RATE[speed][2]) #set TXB0,TXB1 #<15:5> SID 11bit canid #<BIT3> exide,1:extended 0:standard self.WriteBytes(TXB0SIDH,0xFF) self.WriteBytes(TXB0SIDL,0xE0) self.WriteBytes(TXB0DLC,0x40|DLC_8) # self.WriteBytes(TXB1SIDH,0x50) # self.WriteBytes(TXB1SIDL,0x00) # self.WriteBytes(TXB1DLC,0x40 | DLC_8) #Set DLC = 3 bytes and RTR bit*/ #Set RX self.WriteBytes(RXB0SIDH,0x00) self.WriteBytes(RXB0SIDL,0x60) self.WriteBytes(RXB0CTRL,0x60) self.WriteBytes(RXB0DLC, DLC_8) self.WriteBytes(RXF0SIDH,0xFF) self.WriteBytes(RXF0SIDL,0xE0) self.WriteBytes(RXM0SIDH,0xFF) self.WriteBytes(RXM0SIDL,0xE0) #can int self.WriteBytes(CANINTF,0x00)#clean interrupt flag self.WriteBytes(CANINTE,0x01)#Receive Buffer 0 Full Interrupt Enable Bit self.WriteBytes(CANCTRL, REQOP_NORMAL|CLKOUT_ENABLED)# dummy=self.ReadByte(CANSTAT) if( OPMODE_NORMAL != (dummy and 0xE0)): self.WriteBytes(CANCTRL, REQOP_NORMAL|CLKOUT_ENABLED)#set normal mode def Send(self, CAN_ID, CAN_TX_Buf, length1): tempdata = self.ReadByte(CAN_RD_STATUS) self.WriteBytes(TXB0SIDH, (CAN_ID>>3)&0XFF) self.WriteBytes(TXB0SIDL, (CAN_ID&0x07)<<5) self.WriteBytes(TXB0EID8, 0) self.WriteBytes(TXB0EID0, 0) self.WriteBytes(TXB0DLC, length1) for j in range(0, length1): self.WriteBytes(TXB0D0+j,CAN_TX_Buf[j]) if(tempdata&0x04):# TXREQ time.sleep(0.01) self.WriteBytes(TXB0CTRL, 0)#clean flag while(1):#wite if(self.ReadByte(CAN_RD_STATUS)&0x04 != 1): break self.WriteByte(CAN_RTS_TXB0) def Receive(self, CAN_ID): self.WriteBytes(RXB0SIDH, (CAN_ID>>3)&0XFF) self.WriteBytes(RXB0SIDL, (CAN_ID&0x07)<<5) CAN_RX_Buf = [] while(1): if(self.ReadByte(CANINTF) & 0x01): len = self.ReadByte(RXB0DLC) print(len) for i in range(0, len): CAN_RX_Buf.append(hex(self.ReadByte(RXB0D0+i))) # print(self.ReadByte(RXB0D0+i)) break self.WriteBytes(CANINTF, 0) self.WriteBytes(CANINTE,0x01)#enable self.WriteBytes(RXB0SIDH,0x00)#clean self.WriteBytes(RXB0SIDL,0x60) return CAN_RX_Buf if __name__ == '__main__': print("--------------------------------------------------------") can = MCP2515() print("init...") can.Init() print("send data...") id = 0x123 #max 7ff data = [1, 2, 3, 4, 5, 6, 7, 8] dlc = 8 can.Send(id, data, dlc) readbuf = [] # while(1): while(1): readbuf = can.Receive(id) print(readbuf) time.sleep(0.5) print("--------------------------------------------------------")
In this demo code the maximum frame id value is limited to 0x7ff. What is the reason for this and how to remove this restriction? I need to send frames with id 0x18FD6A0A.
Sorted by:
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Using a Raspberry Pi Pico, MCP 2515 and Micropython to transmit frames over CAN

I'm trying to use a Raspberry Pi Pico and MCP 2515 to transmit frames over CAN. For this I'm using CAN bus Module (B) for Raspberry Pi Pico (https://www.waveshare.com/wiki/Pico-CAN-B) and demo code for micropython from the same page (code below).

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