Hi everyone,
I own a Teensy 3.6 which runs a K66. I am currently trying to read the pulses of an encoder using the Quadrature Decoder mode of the FlexTimer Module 1 (FTM1).
First of all, I don't have the encoder with me, so I simulated the signals using the FTM0 Output Compare with the following code:
//initialise Flextimer 1
FTM0_MODE = 0x05; //set write-protect disable (WPDIS) bit to modify other registers
//FAULTIE=0, FAULTM=00, CAPTEST=0, PWMSYNC=0, WPDIS=1, INIT=0, FTMEN=1(no restriction FTM)
FTM0_SC = 0x00; //set status/control to zero = disabled (enabled in main loop)
FTM0_CNT = 0x0000; //reset count to zero
FTM0_MOD = FTM1MODCount; //max modulus = 23 (gives count = 24 on roll-over - 1 MHz)
FTM0_C0SC = 0x14; // CHF=0, CHIE=0 (disable interrupt), MSB=0 MSA=1, ELSB=0 ELSA=1 (output compare - toggle), 0, DMA=0
FTM0_C1SC = 0x14; // CHF=0, CHIE=0 (disable interrupt), MSB=0 MSA=1, ELSB=0 ELSA=1 (output compare - toggle), 0, DMA=0
//configure Teensy pins as outputs
PORTC_PCR1 = PORT_PCR_MUX(0x4);
PORTC_PCR2 = PORT_PCR_MUX(0x4);
//enable system clock (48 MHz), no prescale
FTM0_C0V = 0; //compare value = 0
FTM0_C1V = 0x8000; //compare value = 12
FTM0_SC = 0x0A; // (Note - FTM0_SC [TOF=0 TOIE=0 CPWMS=0 CLKS=01 (System Clock 48 MHz) PS=000 [no prescale divide])
This code works, as I can see the Pulses of 114 Hz on my osciloscope, so I don't think this is part of the problem.
Then, I run the following code in order to set the QD mode on my FTM1 (which is supported by the FTM1 in the K66):
SIM_SCGC6|=0x03000000; //enable FTM1 module clock
PORTA_PCR12 |= 0x300; //MUX = alternative function 3 on Chip Pin 28 (FTM1_CH0) = Teensy Pin 3
PORTA_PCR13 |= 0x300; //MUX = alternative function 3 on Chip Pin 29 (FTM1_CH1) = Teensy Pin 4
FTM1_MODE = 0x04;
FTM1_MODE = 0x05;
FTM1_C0SC = 0; //54
FTM1_C1SC = 0;
FTM1_CNT = 0;
FTM1_MOD = 0;
FTM1_C0SC = 0b00011100; // Set dual-capture both edges
FTM1_C1SC = 0b00011100; // Set dual-capture both edges
FTM1_SC = 0;
FTM1_MOD = 0xFFFF;
FTM1_CNTIN = 0;
FTM1_QDCTRL = 0x1;
FTM1_CNT = 0;
FTM1_SC=0x8;
Using this code I know the following. The MOD register gets modified, the CNT does not count up nor down and the QDCTRL enable bit is set high. I have tryed this code both using the FTM1_CnSC registers and without them (when use them, the CHF bit (interrupt flag) always goes up, even if I disable the interrupts).
If anyone can help me, I would really appreciate it.
PS: I have first tryed reading the other questions on this topic from the Forum, but could not get it working anyways.
