Help needed, crank signal generator. <solved>

[AngelMarc]

Looks like plenty of head room.

[MPC001]

Looks like plenty of head room.

Thanks for sharing

[MPC001]

Looks like plenty of head room.

Seems via 68377 spec (E40 MPU) that max current per pin is 1mA. Total 20mA all pins. 33uA sink measured for each of crk & cam inputs resonates with this. All pins max 5V. (Some are 3.3V).

It's a sensitive little number cruncher. Not much margin in an electrically noisy engine bay. Maybe why the MPC56x series superceded so effectively with a 10+ year reign.

[MPC001]

Now to see how stable a 600Mhz Teensy 4.0 can do these waveforms.

Teensy 4.0 at 150Mhz through 600Mhz up to over 800Mhz, the jitter remained at circa +/- 35rpm . So as I think Antus may have mentioned, not due to lack of clock/power. Maybe an artifact of the 68377 being such a busy beaver doing all that factory code crunching, or IDE abstraction code?

[AngelMarc]

also

EDIT:
833333 divided by TPS number equals RPM. Roughly, there's decimals not accounted for.
Edit sketch with the following to use RPM numbers directly

Code: Select all

int RPM = 9000;
int TPS = (2500000 / RPM) / 3;

Attached an updated version. Expect rounding errors in target vs measured. Those errors will get larger at higher RPM.

[MPC001]

also

EDIT:
833333 divided by TPS number equals RPM. Roughly, there's decimals not accounted for.
Edit sketch with the following to use RPM numbers directly

Code: Select all

int RPM = 9000;
int TPS = (2500000 / RPM) / 3;

Attached an updated version. Expect rounding errors in target vs measured. Those errors will get larger at higher RPM.

Thankyou. Certainly the instability gets worse at high rpm numbers depending on the delay setting. If TPS at 100uS pretty stable with minimal jitter. Change to 99us & it jumps around a lot more.