What's the voltage resolution for the afm circuit?

[Stinky]

What's the resolution at which that the ecu reads the afm input voltage? .008v?

[Bernardd]

5.12/.08=64 I'd say it's .08vdc.

[Stinky]

You're basing that off the vqmap right? The vqmap could use interpolation just like the fuel or ignition maps to provide for better resolution.

[Bernardd]

yes, i'm just going by the vq map. i seem to remember there being an interpolation routine, however i'm not positive it was for the vq map or fuel/timing maps. matt or eric on ztech will most likely have to answer that.

[Matt]

yep its 0.08 volts or 80mv ... the code uses interpolation between the points from memory

[Stinky]

Well I guess what i'm asking is whats the resolution at the a/d converter. If its only .08v then there really isnt any way to do interpolation on the vqmap.

[GZ@hybridka]

I am not sure which A/D converter the R31/Z31 ecu uses, I assume most use the 46510? (like my early z31 here).

I dont think a datasheet was ever located for this chip, but I could be wrong.

The HD46508 used in some 6303 ecus is a 8 (or) 10-bit A/D, but it is loaded as a 10-bit (1024-division) and then divided as necessary in code (like to use as 8 bit, divide by 4)

[Matt]

yep its a 46508 from what we can figure with
- 9/10 bit DAC (2 + 8 bits using two bytes to get from 0 - 512 which is our reading from the AFM)
- outputs for LEDs
- inputs for CAS to trigger interrupts
- inputs for other analogue items like temp, AFM etc, Diag Pot

the other main part that makes it different from the 46508 is it has multiplication circuitry in it since 6802 dont have it (but 6303 do)

i figured out some of the registers and hence USB consult RAM addresses which map to this