|
I'm trying to get speed measurement working with the 56F807 timers, at both low speeds where there is a long time between encoder quadrature edges and at high speeds where very accurate measurement of pulse width is necessary. Pages 95-99 of the following designer reference manual describe exactly what I want to do, but I'm having trouble configuring the timer & decoder control & status registers in a way to implement what is described: http://e- www.motorola.com/files/microcontrollers/doc/ref_manual/DRM023.pdf I can't get Timer A1 & A2 to capture on the PHASEA edges, and the quad counter Here's a summary of my register configuration: Decoder0.ControlReg - set to use Mode2 (b'10), also tried in Mode1 (b'01) - Everything else is set to 0 TIMER A0 IS SET UP AS A QUADRATURE COUNTER, USING THE ENCODER PHASE A & PHASE B INPUT SIGNALS TimerA.Channel0.ControlReg - quadrature count mode (b'100) - primary count source = counter 0 input pin (b'0000) - secondary count source = counter 1 input pin (b'01) - OFLAG: gated clock output while counter is active (b'111) TimerA.Channel0.StatusReg - output is enabled - everything else is 0 TIMER A1 IS SET UP TO COUNT TIMER A0 TICKS TimerA.Channel1.ControlReg - cascaded counter mode (b'111) - primary count source = counter 0 output ('b0100) - secondary count source = counter 0 input (b'00) TimerA.Channel1.StatusReg - input capture mode = capture on both edges (b'11) - input edge flag bit is set to 0 in an interrupt routine (but capture doesn't happen!! why?) TIMER A2 IS SET UP TO COUNT TIME BETWEEN PHASEA & PHASEB EDGES TimerA.Channel2.ControlReg - timer counts primary inputs (b'001) - primary count source = IPbus/1 (b'1000) TimerA.Channel2.StatusReg - input capture mode = capture on both edges (b'11) - input edge flag bit is set to 0 in an interrupt routine (but capture doesn't happen when decoder is set to Mode1) Thanks for any insight you can provide. Erik |