I have been designing a new mainboard for a Megasquirt 3 and i have gotten most of the way through.
During my research i stumbled upon the Speeduino and wanted to add the compatibility for it to the board, as i will make multiple of these boards and i wanted to try the speeduino as an alternative as it gives me access to modify the firmware to my liking.
The specs of the board:
- 12 high speed digital inputs buffered by schmitt triggers and optional 5V pullups (good for hall sensors also)
- 24 analog inputs buffered by op-amps with an active low-pass filter (16 of witch go to a separate teensy 3.6 board and are buffered to 3.3V)
- 4 VR sensor inputs using max9926 conditioners
- 6 isolated EGT amplifiers with open and short detection and can be used with grounded tip sensors for faster reaction speeds. communication over I2C
- 2 knock sensor inputs using a TPIC8101DWR for signal conditioning and wired for communications over SPI
- onboard barometric sensor
- 8 Ignition outputs (5V buffered signal for active coils)
- 8 P&H injector drivers (i added pads for VNLD5090TR low side drivers in case P&H are not desired)
- 8 active low outputs (VNLD5090TR drivers)(one has internal 12V or 5V pullup for tacho signal)
- 2 H-bridge output pairs (used for DBW throttle outputs but can be configured for 4 single push-pull outputs. DRV8873)
- 1 Stepper IAC output (has regular step-stick header so the user can select their own driver)
- 2 12V power inputs with over current protection, over/under voltage protection, surge protection with keep-alive and
reverse battery voltage protection. (keeps the smoke in the chips.)
- has internal buck-boost power supply to keep 5V rails until input goes under 2V. (keeps the ECU happy during cranking)
- 2 5V analog reference outputs (for sensors. 1 for ECU and 1 for GPIO and redundancy that the DBW requires)
- protected 12V and 5V outputs for external circuitry
- CAN-BUS (also used between ECU and GIPO)
Not all pins are used currently and they can be wired however the user wants. probably for extra grounds/shielding, I/O for the GIPO etc.
i was also thinking of adding an onboard wideband amplifier, but there isn't much documentation available and i think its good enough the use the external amplifiers for it. (or if anyone has a good implementation that they are willing to share, i'm all ears... erm.. eyes.. )
At some point i will publish the designs here and/or github for all to use.
Back to business:
Is there a preferred pinout for the teensy 3.6 and 4.1 boards that i should use that is not just a jerry-rigged setup to make it compatible with something else?
if there are different preferred pinouts for 3.6 and 4.1 then i might have headers for both as i might have room to support both configurations.
Also i might need some help to create support for DBW and the TPIC8101 for Speeduino.
I am interested in your thoughts and if there is anyone who also needs way too many sensors and Drive-By-Wire support.