My test car is Toyota Mark 2 '94, RWD, almost stock 1JZ-GTE twinturbo engine with AT, it has easy tireslip at full throttle with 230kpa at first and second gears with 205 street tires, seems good for tests and firmware developing.
Now i have two sensors for experiments, driven at the end of gearbox, 72Hz/100kph, and undriven at the right front wheel, stock ABS sensor with 666Hz/100kph, it is VR, but there is logic output from ABS computer to TRC computer, i use one, but with divider by 10 (simple logic chip helps), so vems input freq is 67Hz/100kph.
Now i try to experiment with second solution from below.
Some ideas about cheap traction
1. Antirev, simple float revlimiter, without speedsensor, or with one speedsensor at driven wheel for geardetect, depend from track condidion therefore unuseful.
2. Float revlimiter, revlimit=f(speed) with 8-16 points, without geardetection, speedsensor at undriven wheel, simple revlimiter. Kevin Black proposal.
3. Same as 2 but with geardetection with second speedsensor, so some experiments with another AtMega interrupt (we have some spare) needed. Revlimiter could be with another calc, more advanced than simple f(speed), it could be: min_speed-max_rpm, 1gear scaler, 2gear scaler, etc. So revlimiter=speed*scaler, but except launch, below minspeed we have max_rpm revlimiter. This solution is easy for my case, one undriven wheel speedsensor is enough, because vems always know gear for AT.
For all solution is good to know actual revlimiter in log.