Using SPI hardware

[harryweb]

As nothing seem's to work... (not using simulation program now but real hardware)
Using now the smallest program to test what's wrong:

'****************************************************************
'*  Name    : master.BAS                                        *
'*  Author  : Herve Helleboid                                   *
'*  Notice  : Copyright (c) 2013 HYTEM                          *
'*          : All Rights Reserved                               *
'*  Date    : 02/11/2013                                        *
'****************************************************************

DEFINE OSC 64


TRISA = %00000000
TRISB = %00000000
TRISC = %10010000
TRISD = %10000000
TRISE = %00000000


ANSELA = %00000000
ANSELB = %00000000
ANSELC = %00000000
ANSELD = %00000000
ANSELE = %00000000

' configuration USART1 (communication RS232 external)
RCSTA1 = $90 ' Enable serial port & continuous receive
TXSTA1 = $20 ' Enable transmit, BRGH = 0
SPBRG1 = 103 ' 9600 Baud @ 64MHz, 0,16%


SSPIF VAR PIR1.3     ' SPI interrupt flag
SSPEN   VAR SSP1CON1.5  ' SSP Enable bit
SS0   var PORTB.3
LED   VAR PORTE.0
slave var byte
i     VAR BYTE           ' loop counter
a     VAR BYTE[6]        ' Holds 6 characters read from slave
BF    VAR SSP1STAT.0

HIGH SS0            'slave not in use

HIGH LED
PAUSE 300
LOW LED


hserout ["rdy",13,10]

Pause 50         
      
SSP1CON1 = %00100010
SSP1STAT = %00000000

SSPIF = 0         ' clear buffer full status


mainloop:
   pause 200
   low SS0
   pauseus 5
   SSP1BUF = "?"
   while BF = 1 : wend
   pauseus 10
   SSPIF = 0
   high SS0
   hserout [SSP1BUF," ",dec SSP1BUF,13,10] ' display received char
   toggle led
   GoTo mainloop     ' do it forever

'***********************************************************************************


' Name        : SLAVE.pbp
' Compiler    : PICBASIC PRO Compiler 2.6
' Assembler   : PM or MPASM
' pic18f45k22 @ 16MHz PLLx4 = 64MHz
'

DEFINE OSC 64

TRISA = %00100000
TRISB = %00000000
TRISC = %10011000
TRISD = %10001000
TRISE = %00000000


ANSELA = %00000000
ANSELB = %00000000
ANSELC = %00000000
ANSELD = %00001000
ANSELE = %00000000


' Allocate RAM
dataout VAR BYTE[8]   ' Data out array
SSPEN   VAR SSP1CON1.5  ' SSP Enable bit
CKP     VAR SSP1CON1.4  ' Clock Polarity Select
SMP     VAR SSP1STAT.7 ' Data input sample phase
CKE     VAR SSP1STAT.6 ' Clock Edge Select bit
SSPIF   VAR PIR1.3    ' interrupt flag - last bit set
i       VAR BYTE      ' loop counter
a       VAR BYTE[6]   ' Holds 6 characters of data
led     var PORTA.4
BF    VAR SSP1STAT.0
           
SSP1CON1 = %00000100 ' configure SPI slave with SS  
CKP = 0            ' clock idle low
CKE = 1            ' transmit on idle to active transition
SSPIF = 0          ' clear SPI interrupt
SMP = 0            ' sample in middle of data
SSPEN = 1

RCSTA1 = $90               ' Enable serial port & continuous receive
TXSTA1 = $20               ' Enable transmit, BRGH = 0
SPBRG1 = 25                ' 38400 Baud @ 64MHz, 0,16%

  
HIGH LED
PAUSE 300
LOW LED
 
mainloop:

   SSP1BUF = "!"       ' send reply   $21  dec = 33
   while BF = 1 : wend
   PAUSEUS 10
   SSPIF = 0
   toggle led
   goto mainloop

Master send "?" and need to receive "!"
doing it forever

AS I can see on my logic analyzer
MASTER send $3F (OK it's ? or decimal 63)
SLAVE send $21 (OK its ! or decimal 33)
This is measured with USBEE SX.

As I have a RS232 hardware connected to the PIC master (TX1) my master prog send to RS232 the received character
instead of receiving "!" (dec 33) it is always " " (dec 32)
sometimes also receiving strange characters

So... I was thinking that last bit is not recognized but:

If I change (slave prog) the character "!" by example by "W" or "0" it works fine every time !

I tried to send other different characters and for some of them, it's good...
For others it's decimal value -1 or decimal value + 1

Any help ?

Regards

[HenrikOlsson]

Hi,
I haven't looked that close at your code yet but have you tried putting the logic analyzer on the UART output of the PIC to verify what it is actually sending? Perhaps there's some baudrate issue, some problem with a USB-COM dongle (if you're using one) or something else on that side of equation. On the other hand I see you're outputting rdy at the start and I expect that to display properly. What if you change that to Ready! does it still display properly?

You could always try:

RCSTA = $90   ' Enable serial port & continuous receive
TXSTA = $24   ' Enable transmit, BRGH = 1
SPBRG = 130   ' 9600 Baud @ 64MHz, -0,02%
SPBRGH = 6
BAUDCON.3 = 1 ' Enable 16 bit baudrate generator

/Henrik.

[harryweb]

Hello Henrik,

Thank you for your message
I have tryed your code and change rdy to ready without any result. I will try tomorrow on another computer (direct RS232 port, no USB dongle) to see if the problem isn't here.

Best Regards

[Archangel]

Are you certain your configs are set correctly to operate that PIC @ OSC 64 ?

[harryweb]

Hi,

@ Henrik
On another computer (real RS232 port) = same result

@Archangel
Hi and thank you for your reply

Do you think I forgot something in config bit ?
I'm not expert... May be you can check my config bits:



Maybe I can try at 16MHz, but I choose this pic because of 64MHz.
Regards

[HenrikOlsson]

Hi,
I had never used the MSSP module in slave mode Before but I just had a play with two 18F25K20 devices, one as master and one as slave.
The master sends the letters "A" to "Z" and outputs both what it sends and what it recieves to the serial terminal.
The slave responds with the letters "Z" to "A". It outputs what it receives and what it sends to the serial terminal.

At this time I did not have time to implement and test the SS-line but apart from that it appears to work as expected.

You might be able to gain some insight into your trouble by looking at these two programs.

Here's the code for the master:

'****************************************************************
'*  Name    : SPI Master.pbp                                    *
'*  Author  : Henrik Olsson                                     *
'*  Notice  : Copyright (c) 2013 [Henrik Olsson]                *
'*          : All Rights Reserved                               *
'*  Date    : 2013-11-12                                        *
'*  Version : 1.0                                               *
'*  Notes   : Designed to run on 18F45K20, AMICUS18 platform.   *
'*          :                                                   *
'****************************************************************
DEFINE OSC 64                       ' Default oscillator speed on the AMICUS18 is 16*4MHz
DEFINE LOADER_USED 1                ' We're using a bootloader.

DEFINE HSER_RCSTA 90h               ' Enable serial port & continuous receive
DEFINE HSER_TXSTA 24h               ' Enable transmit, BRGH = 1
DEFINE HSER_CLROERR 1               ' Clear overflow automatically
DEFINE HSER_SPBRG 138               ' 115200 Baud @ 64MHz, -0,08%

SPBRGH = 0
BAUDCON.3 = 1                       ' Enable 16 bit baudrate generator

TRISC = %10010110                   ' RX, TX, SDO, SDI, SCK, N/U, N/U, CS 
TRISB = %11111111                   ' N/U, N/U, N/U, N/U, N/U, N/U, N/U, N/U

' Aliases for the MSSP module status and control bits.
SSPEN           VAR SSPCON1.5       ' SSP Enable bit  
CKP             VAR SSPCON1.4       ' Clock Polarity Select  
SMP             VAR SSPSTAT.7       ' Data input sample phase  
CKE             VAR SSPSTAT.6       ' Clock Edge Select bit
BF              VAR SSPSTAT.0       ' Buffer full flag.  

' Set up the MSSP module.
CKP = 0                             ' Clock idles low  
CKE = 0                             ' Transmit on idle to active transition.  
SMP = 0                             ' Sample in middle of data 
SSPEN = 1                           ' Enable SPI pins
SSPCON1.0 = 1                       ' Slow down SPI clock to Fosc/16 for now.

i VAR BYTE
Response VAR BYTE

Response = SSPBUF                       ' Dummy read to buffer and BF-flag
    
HSEROUT ["Master start...", 13]
HSEROUT ["TX - RX",13]
Pause 5000

Main:
    For i = "A" to "Z"                  ' Send letters A to Z
        SSPBUF = i                      ' Load buffer with content
        While BF = 0 : WEND             ' Wait for operation to complete
        Response = SSPBUF               ' Read response
        HSEROUT [i, "  -  ", Response, 13]
        PAUSE 10
    NEXT
    
    HSEROUT ["Done.....", 13]

    Pause 5000

Goto Main

And here's the code for the slave:

'****************************************************************
'*  Name    : SPI Slave.pbp                                     *
'*  Author  : Henrik Olsson                                     *
'*  Notice  : Copyright (c) 2013 [Henrik Olsson]                *
'*          : All Rights Reserved                               *
'*  Date    : 2013-11-12                                        *
'*  Version : 1.0                                               *
'*  Notes   : Designed to run on 18F45K20, AMICUS18 platform.   *
'*          :                                                   *
'****************************************************************
DEFINE OSC 64                       ' Default oscillator speed on the AMICUS18 is 16*4MHz
DEFINE LOADER_USED 1                ' We're using a bootloader.

DEFINE HSER_RCSTA 90h               ' Enable serial port & continuous receive
DEFINE HSER_TXSTA 24h               ' Enable transmit, BRGH = 1
DEFINE HSER_CLROERR 1               ' Clear overflow automatically
DEFINE HSER_SPBRG 138               ' 115200 Baud @ 64MHz, -0,08%

SPBRGH = 0
BAUDCON.3 = 1                       ' Enable 16 bit baudrate generator

TRISC = %10011111                   ' RX, TX, SDO, SDI, SCK, N/U, N/U, CS 
TRISB = %11111111                   ' N/U, N/U, N/U, N/U, N/U, N/U, N/U, N/U

' Aliases for the MSSP module status and control bits.
SSPEN           VAR SSPCON1.5       ' SSP Enable bit  
CKP             VAR SSPCON1.4       ' Clock Polarity Select  

SMP             VAR SSPSTAT.7       ' Data input sample phase  
CKE             VAR SSPSTAT.6       ' Clock Edge Select bit  
BF              VAR SSPSTAT.0       ' Buffer Full bit

' Set up the MSSP module.
CKP = 0                             ' Clock idles low  
CKE = 0                             ' Transmit on idle to active transition.  
SMP = 0                             ' Sample in middle of data 

While PortC.4 = 1 : WEND            ' Wait for SCK pin to be idle before enabling MSSP
SSPCON1 = %00100101                 ' Slave mode, no SS

i VAR BYTE
Response VAR BYTE

HSEROUT ["Slave start...", 13]
HSEROUT ["RX - TX", 13]

Main:
    For i = "Z" to "A" STEP -1
        SSPBUF = i                      ' Load buffer
        While BF = 0 : WEND             ' Wait for data to arrive
        Response = SSPBUF               ' Read data from buffer, clears flag.
        HSEROUT [Response, "  -  ", i, 13]
    NEXT

    HSEROUT ["Done...",13]

Goto Main

/Henrik.

[HenrikOlsson]

Hello again,
Looking at the slave code in post #3 above it says

CKE = 1            ' transmit on idle to active transition

The setting and comment does not match, Setting the CKE bit makes the slave, in this case, output data on active to idle state of the clock. But, looking at the master code it is set up to sample the data in the middle of the cycle. I'm not sure if this is the actual problem but comparing it to my examples it's something that differs.

/Henrik.