Page 1 of 1
What's the voltage resolution for the afm circuit?
Posted: Mon Aug 14, 2006 4:46 am
by Stinky
What's the resolution at which that the ecu reads the afm input voltage? .008v?
Posted: Mon Aug 14, 2006 5:43 am
by Bernardd
5.12/.08=64 I'd say it's .08vdc.
Posted: Mon Aug 14, 2006 7:41 am
by 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.
Posted: Mon Aug 14, 2006 1:50 pm
by 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.
Posted: Mon Aug 14, 2006 3:29 pm
by Matt
yep its 0.08 volts or 80mv ... the code uses interpolation between the points from memory
Posted: Tue Aug 15, 2006 11:30 am
by 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.
Posted: Fri Oct 27, 2006 3:32 pm
by 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)
Posted: Fri Oct 27, 2006 11:56 pm
by 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