Revised schematics and pin functions

After a bit more thought, there is now a new set of pin assignments for the Primus micromouse, along with a corresponding schematic.The problem with Primus was that it is not possible to generate two independant pulse trains from the PWM generators. All the PWM channels have to share a common time base.The Output Compare peripherals on the dsPIC30F4011 can generate up to two independant pulse trains in hardware but one of the time bases must come from Timer 2 which is needed for counting steps sent to the motors. One of the fundamental design decisions on Primus is to drive the two steppers at high speeds without any interrupt service routine soaking up processor cycles.It seems that one motor will have to be driven from an OC channel and the other from a PWM channel. (more…)

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A bit of a change to Primus

It seems I made a bit of a mistake in how I thought the dsPIC could drive its PWM module. Consequently, there will have to be some changes.First, what can’t change is the need to use T1CK and T2CK as external inputs to count motor pulses. There are no other choices on the dsPIC30F4011 without using interrupts. Since I anticipate pulse rates of up to 100,000 Hz per wheel, life will be a lot easier not having to service that interrupt rate, even with a fast processor and a very efficient ISR. (more…)

Continue ReadingA bit of a change to Primus