MC9S08QG8 needed help

[mediterranean]

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 ?

[bigmac]

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

[glennp]

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]

[bigmac]

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

[glennp]

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

[mediterranean · Accepted solution]

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

lsra       ;extract SDA

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

lsra         ;extract bit2

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

lsra                                          ;extract bit10

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@”

;

[bigmac]

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