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Re: Datasheet and register question
Thanks for the help Henrik. I still don't understand it. I've been trying for the past four days and I can't get my variables set up correctly. I've been looking at code on here and other places on the internet and I'm more confused than I was before - most of them are in C. The datasheet seems really confusing to me. I think I've wasted more than 100 hours so far.
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Re: Datasheet and register question
I have a hammer in one hand and the 18F4550, along with the MCP2515 are on my table. It would really provide a lot of stress relief.
I'm going to scrap this and just go with an 18F with CAN built in.
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Re: Datasheet and register question
The 4550 is quite commonly supported... not only that but the datasheets seem (to me) to be written properly...
I've not played with CAN, however i (along with a lot of other people on here) know the 4550 very well...
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Re: Datasheet and register question
Hi Christopher,
This may be moot if you've already decided to switch devices but it still seems to me like if you're missing one crucial point. You said that you can't get your variable set up correctly which variables are you talking about here and how do you set them? I don't mean to which values you set them but how do you actually assign your values - whatever value it might be - TO the variable?
The reason I ask is because I still think you may be missing the point that in order for the MCP2515 to work you need to set IT up - ie assign values to the regsiters that are IN the MCP2515. The MCP2515 is an intelligent device, it's not like a MAX232 which has nothing to set up. When you say variables it sounds as if you're still trying to assign values to variables that you create in the PIC and that won't work.
Are you using SHIFTOUT to write the values or do you use the MSSP module?
If it was me I start by making a routine which write values to the MCP2515. Then I'd make a routine which reads values from the MCP2515 to verify that the write routine is working properly.
Can you post some code of your current attempts?
/Henrik.
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Re: Datasheet and register question
Thank you for your substantive post. It has helped me greatly.Originally Posted by comwarrior
I'm using the MSSP. I think my commands are getting to the MCP but I'm guessing my problem lies in one of these places:Are you using SHIFTOUT to write the values or do you use the MSSP module?
If it was me I start by making a routine which write values to the MCP2515. Then I'd make a routine which reads values from the MCP2515 to verify that the write routine is working properly.
Can you post some code of your current attempts?
CNF1, CNF2, CNF3, SSPCON, SSPSTAT OR BAUDCON. It could be anywhere else too. Basically, the entire program is suspect. Thanks for the help Henrik. Maybe you can spot some issues with what I wrote:
Code:INCLUDE "modedefs.bas" ' DEFINE OSC 20 '============================================================================== ' SETTINGS ' ============================================================================== '76543210 '76543210 TRISA = %11111111: PORTA = %00000000 TRISB = %00010001: PORTB = %00010000 TRISC = %00000000: PORTC = %00000001 TRISD = %11111111: PORTD = %00000000 TRISE = %00010000: PORTE = %00010111 ADCON0 = %00000000 ADCON1 = %00000000 ADRESH = %00000000 ADRESL = %00000000 CMCON = %00000000 SSPSTAT = %11000100 SSPCON1 = %10110001 BAUDCON = %00001111 '=============================================================================== ' Register Mapping '================================================================================ CANSTAT CON $0E CANCTRL CON $0F BFPCTRL CON $0C TEC CON $1C REC CON $1D CNF3 CON $28 CNF2 CON $29 CNF1 CON $2A CANINTE CON $2B CANINTF CON $2C EFLG CON $2D TXRTSCTRL CON $0D '' Recieve Filters '' RXF0SIDH CON $00 RXF0SIDL CON $01 RXF0EID8 CON $02 RXF0EID0 CON $03 RXF1SIDH CON $04 RXF1SIDL CON $05 RXF1EID8 CON $06 RXF1EID0 CON $07 RXF2SIDH CON $08 RXF2SIDL CON $09 RXF2EID8 CON $0A RXF2EID0 CON $0B RXF3SIDH CON $10 RXF3SIDL CON $11 RXF3EID8 CON $12 RXF3EID0 CON $13 RXF4SIDH CON $14 RXF4SIDL CON $15 RXF4EID8 CON $16 RXF4EID0 CON $17 RXF5SIDH CON $18 RXF5SIDL CON $19 RXF5EID8 CON $1A RXF5EID0 CON $1B '' Receive Masks '' RXM0SIDH CON $20 RXM0SIDL CON $21 RXM0EID8 CON $22 RXM0EID0 CON $23 RXM1SIDH CON $24 RXM1SIDL CON $25 RXM1EID8 CON $26 RXM1EID0 CON $27 '' Tx Buffer 0 '' TXB0CTRL CON $30 TXB0SIDH CON $31 TXB0SIDL CON $32 TXB0EID8 CON $33 TXB0EID0 CON $34 TXB0DLC CON $35 TXB0D0 CON $36 TXB0D1 CON $37 TXB0D2 CON $38 TXB0D3 CON $39 TXB0D4 CON $3A TXB0D5 CON $3B TXB0D6 CON $3C TXB0D7 CON $3D '' Tx Buffer 1 '' TXB1CTRL CON $40 TXB1SIDH CON $41 TXB1SIDL CON $42 TXB1EID8 CON $43 TXB1EID0 CON $44 TXB1DLC CON $45 TXB1D0 CON $46 TXB1D1 CON $47 TXB1D2 CON $48 TXB1D3 CON $49 TXB1D4 CON $4A TXB1D5 CON $4B TXB1D6 CON $4C TXB1D7 CON $4D '' Tx Buffer 2 '' TXB2CTRL CON $50 TXB2SIDH CON $51 TXB2SIDL CON $52 TXB2EID8 CON $53 TXB2EID0 CON $54 TXB2DLC CON $55 TXB2D0 CON $56 TXB2D1 CON $57 TXB2D2 CON $58 TXB2D3 CON $59 TXB2D4 CON $5A TXB2D5 CON $5B TXB2D6 CON $5C TXB2D7 CON $5D '' Rx Buffer 0 '' RXB0CTRL CON $60 RXB0SIDH CON $61 RXB0SIDL CON $62 RXB0EID8 CON $63 RXB0EID0 CON $64 RXB0DLC CON $65 RXB0D0 CON $66 RXB0D1 CON $67 RXB0D2 CON $68 RXB0D3 CON $69 RXB0D4 CON $6A RXB0D5 CON $6B RXB0D6 CON $6C RXB0D7 CON $6D '' Rx Buffer 1 '' RXB1CTRL CON $70 RXB1SIDH CON $71 RXB1SIDL CON $72 RXB1EID8 CON $73 RXB1EID0 CON $74 RXB1DLC CON $75 RXB1D0 CON $76 RXB1D1 CON $77 RXB1D2 CON $78 RXB1D3 CON $79 RXB1D4 CON $7A RXB1D5 CON $7B RXB1D6 CON $7C RXB1D7 CON $7D '=============================================================================== ' Register Bit Masks '=============================================================================== DLC_0 CON $00 DLC_1 CON $01 DLC_2 CON $02 DLC_3 CON $03 DLC_4 CON $04 DLC_5 CON $05 DLC_6 CON $06 DLC_7 CON $07 DLC_8 CON $08 '=============================================================================== ' ' CAN SPI commands '=============================================================================== ' ' CAN_RESET $C0 ' CAN_READ $03 MCPWRT CON $02 ' CAN_RTS $80 ' CAN_RTS_TXB0 $81 ' CAN_RTS_TXB1 $82 ' CAN_RTS_TXB2 $84 ' CAN_RD_STATUS $A0 ' CAN_BIT_MODIFY $05 ' CAN_RX_STATUS $B0 ' CAN_RD_RX_BUFF $90 ' CAN_LOAD_TX $40 '=============================================================================== ' ALIAS & MODIFIERS '============================================================================== CS VAR PORTB.4 ' CS LINE SCLK VAR PORTB.1 ' CLOCK LINE SDI VAR PORTB.0 ' DATA INPUT LINE SDO VAR PORTC.7 ' DATA OUTPUT LINE SENDLED VAR PORTA.5 ' LED TO INDICATE THE PROGRAM IS IN THE SENDING ROUTINE MAINLED VAR PORTE.2 ' LED TO INDICATE THE PROGRAM IS IN THE MAIN ROUTINE INT VAR PORTB.5 ' INTERRUPT OUTPUT FROM 18F4550 MCPRST VAR PORTC.0 ' RESET LINE FOR MCP2515 SW_LOAD VAR PORTA.4 ' BUTTON CONNECTED TO 18F4550 TO START SENDING DATA (WHEN IMPLEMENTED) '=============================================================================== ' SOFTWARE VARIABLES '=============================================================================== DATAOUT VAR BYTE 'FIRST BYTE OF DATA TO BE SENT MCPREG VAR BYTE 'ADDRESS OF FIRST BYTE OF DATA TO BE SENT '============================================================================== ' RESET MCP2515 '============================================================================== LOW MCPRST ' COMMAND TO RESET THE MCP2515 (SOFTWARE) PAUSE 1 HIGH MCPRST PAUSE 20 '============================================================================== ' INITIALIZE MCP2515 '============================================================================== LOW CS SSPBUF = MCPWRT ' COMMAND TO WRITE TO THE MCP2515 PIR1.3 = 0 WHILE PIR1.3=0 :WEND MCPREG = CANCTRL ' PUT THE MCP2515 INTO CONFIGURATION MODE DATAOUT = %10001010 GOSUB SENDCANDATA MCPREG = CNF3 'CNF3 - CONFIGURATION REGISTER 3 DATAOUT = $07 GOSUB SENDCANDATA MCPREG = CNF2 'CNF2 - CONFIGURATION REGISTER 2 DATAOUT = $BA GOSUB SENDCANDATA MCPREG = CNF1 'CNF1 - CONFIGURATION REGISTER 1 DATAOUT = $03 GOSUB SENDCANDATA MCPREG = TXB0SIDL 'TRANSMIT BUFFER 0 FOR SIDL DATAOUT = %10000000 GOSUB SENDCANDATA MCPREG = TXB0SIDH 'TRANSMIT BUFFER 0 FOR SIDH DATAOUT = %00000001 GOSUB SENDCANDATA MCPREG = CANCTRL 'PUT THE MCP2515 BACK INTO NORMAL MODE DATAOUT = %00001010 GOSUB SENDCANDATA HIGH CS '============================================================================== ' MAIN PROGRAM FOR MCP2515 '============================================================================== PROGRAMSTART: HIGH SENDLED PAUSE 50 LOW CS SSPBUF = $02 ' COMMAND TO WRITE TO THE MCP2515 PIR1.3 = 0 WHILE PIR1.3=0 :WEND MCPREG = CANINTE ' DISABLE ALL INTERRUPTS DATAOUT = %00000000 GOSUB SENDCANDATA MCPREG = TXB0CTRL ' FLAG THE TRANSMIT BUFFER - - 11=HIGH, 10=MEDIUM, 01=LOW, 00=LOWEST DATAOUT = %00001011 GOSUB SENDCANDATA MCPREG = TXB0SIDL ' TRANSMIT BUFFER 0 FOR SIDH DATAOUT = %00110010 GOSUB SENDCANDATA MCPREG = TXB0SIDH ' TRANSMIT BUFFER 0 FOR SIDH DATAOUT = %00110001 GOSUB SENDCANDATA MCPREG = TXB0DLC ' NUMBER OF BYTES TO BE TRANSMITTED IN CAN FRAME DATAOUT = %00000010 GOSUB SENDCANDATA MCPREG = TXB0D0 ' DATA PACKET FOR BYTE 1 DATAOUT = %00000001 GOSUB SENDCANDATA MCPREG = TXB0D1 'DATA PACKET FOR BYTE 2 DATAOUT = %00000100 GOSUB SENDCANDATA HIGH CS LOW sendled pause 50 goto PROGRAMSTART '=============================================================================== ' SEND CAN DATA SECTION '=============================================================================== SENDCANDATA: SSPBUF = MCPREG ' ADDRESS TO LOAD THE DATA TO THE MCP2515 PIR1.3 = 0 WHILE PIR1.3=0 : WEND SSPBUF = DATAOUT 'DATA BEING LOADED TO THE MCP2515 ON MCPREG PIR1.3 = 0 WHILE PIR1.3=0 : WEND RETURN
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Re: Datasheet and register question
Hi Christopher,
OK, you're making progress, don't give up!
You have ADCON1 = 0 which will have all 13 analog pins set as analog, you probably want to turn the analog stuff OFF by setting ADCON1 = 15. For example RB0 and RB1 are AN12 and AN10 respectively but they are also the SDI and SCK pins for the MSSP module - that may or may not be part of the problem.
You have CMOCON = 0 which will leave both analog comparators ON, to turn them OFF on the 4550 you need to do CMCON = 7 - may or may not be part of the problem depending on exactly which pins they are on and what you're using, or trying to use, them for - I haven't looked into it.
The MCP2515 SPI timing diagrams show the SPI clock idling LOW. You have SSPCON1.4 set to 1 which will make the clock idle HIGH, ie wrong polarity.
Well, that's three things I see that may have something to do with it. Try adressing those, then try capturing the signals with your scope and see if they look anything like the timing diagrams in the MCP2515 datasheet.
/Henrik.
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Re: Datasheet and register question
Jag är trött.....snälla hjälp mig!
It's 1am here so hopefully this post is clear enough and someone can help me! I've been adjusting settings and trying new things and it still doesn't work. Here is what it boils down to. This is a picture of the working code from Microchip (if I knew C I'd be done already).
Channel 1 (Yellow) SDO from 18F4550
Channel 2 (Blue) CS from 18F4550
Channel 3 (Purple) TXCAN from MCP2515
Channel 4 (Green) CLK from 18F4550?
This is what I'm looking to achieve.
This is what my code looks like:
At least it's not that much different and I'm in the ballpark. What I can see is the signals are similar but way more compressed. It seems like a timing issue but I really don't know.
I adjusted the oscilloscope to the same seconds/division as the Microchip example and it's very compressed. It looks like this:
I tried adjusting the HSPLL to HS and that seemed to make things a little better but didn't do much as far as a working program. The clock still looks strange when I compare it with the Microchip code.
The other things I see wrong:
1. The code I'm using is sending one data packet, along with SIDH and SIDL. I setup Microchip's program to do the same thing. I can't figure out why but my code is sending a lot more than a few bytes of data. In fact, it overloads the demo program that Microchip supplies and shuts it down.
2. Microchip's code sends the CAN data after the CS line goes high. For some reason, my program sends it halfway through the data transfer and my SDO line and the CAN output line are sending data at the same time. I did it once (send data after the CS line went high) but I can't remember what I did.
3. I'm confused with the CKE/CKP bits and not sure what I need to set them as. I see this "mode 0,0" advertised in the MCP2515 datasheet but it literally means nothing to me and I'm sure it's pretty important.
4. Did I properly set my BAUDCON?
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