topic Re: MC9S08QG8 needed help in CodeWarrior for MCU

MC9S08QG8 needed help

mediterranean — Mon, 10 May 2010 02:58:33 GMT

hello everyone ! Recently i have started to work with assembly. I have school project on MC9S08QG8 with I2C.

i need to write code to control LCD.

What can i start with ?

Re: MC9S08QG8 needed help

bigmac — Mon, 10 May 2010 20:34:21 GMT

Hello, and welcome to the forum.

You will need to be more specific about the LCD display module that you are using. The majority of alphanumeric display modules do not use an IIC (I2C) interface.

Regards,

Mac

Re: MC9S08QG8 needed help

glennp — Fri, 14 May 2010 07:22:43 GMT

Hi, I am also using a QG8 for the first time and codewarrior 6.2 also. (for 1st time) I want to use IIC to communicate with a device and am having a lot of trouble with it. Understanding what to do with IIC mainly. Assembler only !

I want to send some bytes, then read back some data for a IIC device.

I have initialised IIC as follows: Not using interrupts

; ### Init_IIC init code
                        ; IICA: ADDR7=1,ADDR6=1,ADDR5=1,ADDR4=1,ADDR3=1,ADDR2=1,ADDR1=1
        MOV     #$DE,IICA
                        ; IICF: MULT1=0,MULT0=1,ICR5=0,ICR4=0,ICR3=0,ICR2=0,ICR1=0,ICR0=0
        MOV     #$40,IICF
                        ; IICS: TCF=0,IAAS=0,BUSY=0,ARBL=1,SRW=0,IICIF=1,RXAK=0
        MOV     #$12,IICS              ; Clear the interrupt flags

                        ; IICC: IICEN=1,IICIE=0,MST=1,TX=1,TXAK=0,RSTA=0   NOTE no INT enabled
        MOV     #$B0,IICC

Initially at least, I just want to be able to get some IIC data out of the device without worrying about interrupts etc. I had thought the above code would set up the IIC port and all I had to do then was to write the data to the IIC data reg. Nothing happens. I write to the IICD data reg and then loop looking for data sent (bit 7 of IICS. It seems to pass that test as it keeps going past that point, suggesting the data has 'gone' ie Transfer complete

ie, I have:

I2CTxByte:
       sta      IICD

       ;and loop till sent ie check flag ?????????????
        brclr   7,IICS,*

Apart from that, I am at loss to understand compeltely how to inititate the start sequence, send data and stop sequence.

Should I bset MST of the IICC to do a START condition on IIC? ie BSET MST,IICC (and have it cleared in the initialisation)

Then store the data to be sent into the IICD data reg.

Then keep storing data into the IICD reg while checking for Transfer complete.

Then send STOP condition but how ? bclr MST,IICC ?

Would someone be so kind as to offer some (assembler) code snippets to:

initialise the IIC port (I am using porta, the default)

show how to set start, data and stop condtions (for non interupt mode)

Glenn

[Melbourne, Australia]

Re: MC9S08QG8 needed help

bigmac — Fri, 14 May 2010 10:41:08 GMT

Hello Glenn,

There are two application notes that pertain to the IIC module, AN3048 and AN3291. The latter is the more general note and includes a number of MCU device families for an EEPROM application. Unfortunately both provide code written in C.

However, the following old thread may be of interest, where an attempt was made to convert some of the C functions given in AN3291 into assembly code.

https://community.freescale.com/message/30569#30569

There was also a further old thread where some problems with AN3291 code were discussed, and a solution proposed. I am not sure whether the assembly code from above thread reflected the contents of this thread.

https://community.freescale.com/message/21354#21354

Regards,

Mac

Re: MC9S08QG8 needed help

glennp — Mon, 17 May 2010 07:58:16 GMT

Thanks for the reply, Mac,

There are many 'pleas' for help with IIC using assembler in this Forum. I eventually found (in the forum) a snippet of code to address an eeprom peripheral in slave mode. I managed to adapt this for my application which is to send a series of bytes to a slave, then read one byte back. Part of my problem was omitting the 'repeat start'

Below are my code (snippets), polling used, better with a timeout in each and will add later

;ADDRESS FOR SLAVE
IIC_SLAVE EQU $DE ; This is the address for TFT pcb

;called at Micro init. out of reset.
;to initialise IIC mode.
;
Init_I2C:

         BSET   IICC_IICEN,IICC     ; Enable I2C
          BSET   IICC_TXAK,IICC      ; No ACK generated by master
          BCLR   IICC_MST,IICC       ; Select slave mode
          MOV    #$8B,IICF                 ; Set speed 50kHz for Bus = 8MHz
                                                          ; 50k -> $8B, 100k -> $4B
          BCLR   IICS_SRW,IICS       ; Set R/W bit = 0
          RTS

;entry to send slave address to slave deive:

IIC_write_byte: ; NB uses polling

          BCLR   IICC_TXAK,IICC
          LDA    IICC
          ORA    #$30                ; Generate START condition
          STA    IICC

          LDA      #IIC_SLAVE                  ;get slave address
          STA    IICD                                  ; Send byte
          BRCLR IICS_IICIF,IICS,*        ; Wait until flag is set
          BSET   IICS_IICIF,IICS              ; Clear flag
          BRSET IICS_RXAK,IICS,*        ; Wait until RXAK clear - slave ACK

.........................

........................

;loop to send number of bytes required:- (loop code not shown):-

I2CTxByte:
          STA    IICD                                  ;data out
          BRCLR IICS_IICIF,IICS,*       ; Wait until flag is set
          BSET   IICS_IICIF,IICS           ; Clear flag
          BRSET IICS_RXAK,IICS,*    ; Wait until RXAK clear - slave ACK

.................

..............

Now, send slave address and READ coomand (bit 0 of slave address = 1)

;Then get data back in this case one byte required.

; send slave address and read back one byte, NB requires repeat start
          BSET   IICC_RSTA,IICC      ; Setup << repeated start >>
          LDA    #IIC_SLAVE                ; get slave's address
          ORA    #$01                            ; Set RW bit
          STA    IICD                              ; Send byte
          BRCLR IICS_IICIF,IICS,*   ; Wait until flag is set
          BSET   IICS_IICIF,IICS         ; Clear flag
          BRSET IICS_RXAK,IICS,*    ; Wait until RXAK clear - slave ACK

          BCLR   IICC_TX,IICC            ; Setup to receive
          BSET   IICC_TXAK,IICC      ; Acknowledge disable
          LDA    IICD                             ; Dummy read
          BRCLR IICS_IICIF,IICS,*   ; Wait until flag is set
          BSET   IICS_IICIF,IICS       ; Clear flag
          BCLR   IICC_MST,IICC       ; Generate STOP
          LDA    IICD                            ; Read data byte

;analyze /save data read back etc

Glenn

Re: MC9S08QG8 needed help

mediterranean — Thu, 20 May 2010 18:04:04 GMT

hi everone.I found my solution .Thanks anyway !

SDA equ !6 ;I2C SDA signal

SCL equ !5 ;I2C SCL signal

gSDA rmb 1 ;contains I2C data

ChipAdr rmb 1 ;contains slave I2C address

ChipReg rmb 1 ;contains MC9S08QG8 internal register address

SendI2C:

bset SDA,PTBDD ;set PORTB Bit6 as Output

lda ChipAdr ;get the I2C byte to send

jsr sendStart ;send the Chip Address

lda PORTD

lsra ;extract SDA

bcc sChipReg ;SDA = Low −> acknowledge OK

jmp ACKerror ;SDA = High −> no acknowledge, error

;send the MC9S08QG8 register address = $01

sChipReg bclr SDA,PTBD ;force I/O = L

bset SDA,PTBDD ;set PORTB Bit6 as Output to write

;to the NCP5602

bclr SCL,PTBD ;set CLOCK = L

lda ChipReg ;send the internal register address

jsr sendByte

lda PORTD

lsra ;extract bit2

bcc sDATA ;SDA = Low −> acknowledge OK

jmp ACKerror ;SDA = High −> no acknowledge, error

;send the MC9S08QG8 data byte

SDATA

bclr SDA,PTBD ;set PORTB Bit6 as Output to write to MC9S08QG8

bset SDA,PTBDD

bclr SCL,PTBD ;set CLOCK = L

lda gSDA

jsr sendByte

bclr SDA,PTBDD ;set PORTD Bit10 as Input to read

the ACKNOWLEDGE

lda PORTD

lsra ;extract bit10

bcc exitI2C ;SDA = Low −> acknowledge OK

jmp ACKerror ;SDA = High −> no acknowledge, error

exitI2C

bclr SDA,PTBD

bset SDA,PTBDD

bclr SCL,PTBD

jsr delay5

bset SCL,PTBD

jsr delay5

bset SDA,PTBD

rts ;I2C transmission completed

;

ACKerror ldhx #mes2 ;get I2C error message

Jmp finish ;error

rts

;

sendStart

pshx ;start the I2C link

bset SCL,PTBD ;preset Clock = H

ldx #$08 ;preset I2C clock bit count

bclr SDA,PTBD ;force DATA = L to Start the frame

nop

nextBit

bclr SCL,PTBD ;CLOCK = LOW

lsla ;rotate 8 bits into Carry

bcs sendHbit

bclr SDA,PTBD ;SDA = L

bra posCLK

sendHbit bset SDA,PTBD ;SDA = H

posCLK bset SCL,PTBD ;CLOCK = High

decx ;decrement clock count

bne nextBit

bclr SCL,PTBD ;CLOCK = L

bclr SDA,PTBDD ;set PORTD Bit2 as Input to read

;the ACKNOWLEDGE

jsr delay5 ; wait to make sure the signal

;is stable

bset SCL,PTBD ;CLOCK = H

jsr delay5

pulx

rts

;

sendByte

pshx ;send one byte to the I2C port

bset SCL,PTBD ;preset Clock = H

ldx #$05 ;preset I2C clock bit count

lsla

nop

nextBitD

bclr SCL,PTBD ;CLOCK = LOW

lsla ;rotate 8 bits into Carry

bcs sendHbitD

bclr SDA,PTBD ;SDA = L

bra posCLKD

sendHbitD bset SDA,PTBD ;SDA = H

posCLKD bset SCL,PTBD ;CLOCK = High

decx ;decrement clock count

bne nextBitD

bclr SCL,PTBD ;CLOCK = L

bclr SDA,PTBDD ;set I/O as Input

jsr delay5

bset SCL,PTBD ;CLOCK = H

jsr delay5

pulx

rts

nop finish ;finish not operating

;

mes2 db “I2C error : no ACK return@”

;

Re: MC9S08QG8 needed help

bigmac — Fri, 21 May 2010 00:36:56 GMT

Hello,

The code that you are using is actually "bit banging" the IIC interface, normally utilized when IIC peripheral hardware is not available. Since the device you are using does have an IIC hardware module, the communications would be significantly faster if this were to be utilised.

The code posted by Glenn P. shows the use of the IIC module.

Regards,

Mac