BennVenn wrote:
NVRAM: do you find a pull up suffices with keeping CE high? I was thinking decoupling the supply via a diode to keep a resovoir cap charged and then use that for the pullup vcc. It'll be there long after the cpu is forced into reset by the power controller ic.
Do you mean CE, or WE?
A 10k pull-up on the WE line works fine for me.
edit:
Wouldn't there be a risk of WE being kept low on startup while the cap charged up?
And with the risk of WE being held low on startup - As far as i know 5v is there when the battery is connected. Without it the CPU couldn't retain its RAM. But even if it wasn't and was only present with ignition, the connection between WE and the cap will be via a 10k resistor or equiv. The CPU will have complete control over the WE pin as long as it is not tri-state, which is the condition it is in when /reset is asserted. So if the CPU is running, WE is not influenced. When power dips below ~4v the browout IC takes over, resets the CPU which floats the WE pin and the voltage left in the cap will pull WE high. As for charging, it will be charged via a shotky diode so it should track VCC pretty much instantly minus the .45v drop. We're only talking 1uf or less
Dylan wrote:Sorry I just re read your post. If the 12P ADX dial said 23 and your timing on the motor matched then all is good. Was it idling at that time?
Idle was at 1000rpm as requested, TPS 0%, IAC 29steps. I'll confirm the engine run time and temp
Dylan wrote:In diagnostic and normal mode there's a difference. In diagnostic mode the module controls the timing, in normal mode the ECU does. There's a possibility for some error between the 2 if there's a reference angle difference.
There's a table for temperature correction to the timing but it's only 2 or 3 degrees each way. Ads some when cold removes some when hot. But between say 40 and 90 deg coolant it's as commanded from the main table.
sorry dylan, this is incorrect.
in diagnostic mode, the ECU controls the timing, but commands 10 degrees. this is why you compare module timign and diagnostic timing to make sure they match and the reference angle is correct.
OK, I'll need to do some testing of the stock brownout IC to see its thresholds. The Dallas IC will disable WE if vcc is lower than 4.5 or 4.75 depending on which variant you choose. On the topic of battery backed NVRAM, STmicro also sell their own version. Idential specs to the Dallas IC at only $20 (for the 70deg spec version) 10yr guaranteed retention on battery power etc... I've got one of those coming for testing too. FRAM seems like the way ahead though for a long term solution.
I've noticed a lack of electrolytics in the Delco 808. Good long life design, they instead chose to use hundreds of ceramic 1206 SMD's. The STK hybrid NVRAM requires a VCC fall from 5v to 3.3v of 10us. I'll scope VCC tonight to see how far off it is, and how much additional capacitance will be required. FRAM doesn't require this though fake FRAM IC's are becoming very popular which is not the case with the STK's.
Dylan wrote:In diagnostic and normal mode there's a difference. In diagnostic mode the module controls the timing, in normal mode the ECU does. There's a possibility for some error between the 2 if there's a reference angle difference.
There's a table for temperature correction to the timing but it's only 2 or 3 degrees each way. Ads some when cold removes some when hot. But between say 40 and 90 deg coolant it's as commanded from the main table.
sorry dylan, this is incorrect.
in diagnostic mode, the ECU controls the timing, but commands 10 degrees. this is why you compare module timign and diagnostic timing to make sure they match and the reference angle is correct.
If it was in closed loop idle mode then it would read from that table.
What's the main table in that map? Was it the main table you were seeing the 10 deg bubble tracing on?
Yeah, well it was floating between 10 and 10.7 cells so somewhere in that ball park. But makes complete sense if it was going off the closed loop table. I'm pretty sure it had 'closed loop idle enabled' or something too. Nice.
Just piecing together a spark map from an original 1960's distributor vac and centrifugal advance curves.
