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Re: Data on 16034984
Andy Whittaker - Chester UK wrote:
>
> However, does anyone have details on any of the chips...
I've included some code snippets that access the A/D converter and the FMD
chip. They are from ASBX for the 1227808 ('165). I'd be surprised if your
code is not very similar. I apologise to those who are "code challenged" for
the size of this post, but I think there are enough people on this list who
are reasonably au fait with GM code (BTW, mnemonics are from my own DHC11
that I will be making available soon).
The A/D chip appears close to a Texas Instruments TLC452 or
Motorola MC145041
Try: http://www.ti.com/sc/docs/products/analog/tlc542.html
;
; Read A/D converter - ($ECD8)
;
; In: A = A/D command
;
; Out: A = A/D result, or 0 if there was an error (check Carry flag)
; Carry Flag = Clear -> Okay, Set -> Failure
;
; The test channel is used to determine if an error exists with
; the reference voltage - which should return a count of 127
;
ReadADC:
pushB
pushX
ldX #$4002 ;parallel I/O port
bclr 0, X, #bit3 ;Select A/D converter
call SpiTxRx ;Read, use mux address in A
tAB ;result to B
ldaA #7 ;timer value
@0
decA ;short delay
bne @0
ldaA #$B0 ;select the test channel (12)
call SpiTxRx ;read A/D test channel
bcs @1 ;SPI error?
cmpB #127-10 ;less than 127-10 ?
bls @1 ;no
cmpB #127+10 ;more than 127+10 ?
bhi @1 ;no
clc ;therefore no error
jr @2 ;ok exit
@1
clrA ;error - set result = 0
sec ;show error
@2
bset 0, X, #bit3 ;deselect A/D converter
popX
popB
ret
;
Here's some code for the FMD...
Note that for ASBX, location $02C holds the Data output byte. Note also
that I have called the "Output byte" (as described by Ludis below) as the
"first FMD status byte"
Ludis Langens wrote:
> Output byte:
> bit7: Input source select; 0 == inputs, 1 == status
> bit6: IRQ enable (IRQ on falling edge of ESTHi)
> bit5: ??
> bit4: Pin 8 source; 0 == pin 9 input, 1 == bit3
> bit3: Pin 8 output data when bit4 is set
> bit2: EST enable
> bit1: Limp home watchdog bit
> bit0: CTS pullup; 0 == 4K ohm, 1 == 348 ohm
>
> Input byte:
> bit7: Pin 41 input
> bit6: Pin 40 input
> bit5: Pin 39 input
> bit4: Pin 38 input
> bit3: Pin 37 input
> bit2: Pin 36 input
> bit1: Pin 35 input
> bit0: Pin 34 input
>
> Status byte:
> bit7: ??
> bit6: Pin 52 input (from injector output)
> bit5: ??
> bit4: 0 == 6 or 8 cylinder
> bit3: 0 == 4 or 8 cylinder
> bit2: ??
> bit1: ??
> bit0: ??
>
> Once this chip asserts it's IRQ output, the only way to deassert it is
> to write a zero to the IRQ enable bit.
>
> The watchdog bit needs to be written with alternating values faster than
> a certain rate, otherwise the limphome mode is forced.
>
> The high bit of the output byte chooses between response bytes
> (input/status) for that very SPI transfer.
>
> Esoteric data: The chip select must be dropped and asserted for each
> SPI transfer. If it isn't, then subsequent SPI transfers simply rotate
> through an internal shift register. The internal register is only 7
> bits long - the first SPI bit doesn't use the shifter.
> May I first congratulate Ludis on a great, informative site! As some of you
> may well be aware, I'm currently disassembling the ECU code in my Lotus
> Esprit and having the circuit diagram in front of me has been a great help.
> My Lotus ECU is very similar to the 1227727 with four plugs on the outside.
;
; FMDbyte1 ($ED03) - Read the 1st FMD status byte (command bit 7 = 0)
;
FMDbyte1:
bclr L002C, #bit7 ;clear bit 7 FMD Command/Output Data b
jr FMDio
;
;
; FMDbyte2 ($ED08) - Read the 2nd FMD status byte (command bit 7 = 1)
;
FMDbyte2:
bset L002C, #bit7 ;set bit 7 to select 2nd status byte
;
;
; FMDio ($ED0B) - FMD I/O Write and Read the FMD output/status
;
; The FMD is read/written by calling the SPI I/O routine.
; Bit 7 of the command byte selects which status byte is returned
; FMDio is called to output a value, it will return the status byte
; (1st or 2nd) selected by the last FMDbyteX call (unless L00C2 is
; adjusted!)
;
FMDio:
pushX
ldX #$4002
bset 0, X, #bit2 ;Select FMD (CPU's PORT22 output)
ldaA L002C ;FMD command/output byte
call SpiTxRx
bclr 0, X, #bit2 ;Deselect FMD
popX
ret
;
;
; SpiTxRx - SPI transmit and receive routine ($ED1C)
;
; A holds byte to send to the currently selected SPI device
; The device is assumed to be selected by accessing $4002 and
; setting PORT22 for the FMD, or PORT23 for the A/D chip.
;
; In: A = Output byte to SPI device
;
; Out: A = byte received from the SPI device (0 for error).
; C flag: Clear = okay,
; Set = error
;
SpiTxRx:
pushX
staA L4000 ;byte to Tx on SPI
ldX #L4001
bclr 0, X, #bit7 ;Clear B7 of $4001 to transmit
ldaA #22 ;timeout value
clc ;Carry Flag = 0
@0
brset 0, X, #bit7, @1 ;wait until READY=1
decA ;track timeout count
bne @0 ;loop waiting
sec ;timeout! - show error
jr @2 ;error exit, Carry Flag is set
@1
ldaA L4000 ;read byte the SPI returned
@2
popX ;or 0 with Carry Flag set
ret
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