Three phase timer problems

Hi,

I'm trying to control a  brushed DC motor. The board has a drive circuit that takes a pwm and a direction signal. I've tried to configure the three phase timer to only use outputs v, v(neg) and timer TA1 to control the motor. I've managed to set up the timer so I get a pwm out. The problem is that I can not change the duty cycle of the pwm (TA1 register).

When I step through the code I see that I can not seem to change ICTB2 register. I want to set it to 0x01 but it remains on the value 0x9F.

void

//Disable IRQ

asm("FCLR I"); //TODO Fixa macro

//==========================================

// Set PRCR register

//==========================================

//According to datasheet, you need to use move to set this register - use temp variable?

temp = ictb2;

temp &= 0x01;

//Trigger interrupt every time b2 underflows.

//==========================================

// Set PRCR register - WR disable

//==========================================

prcr = 0x02;

//==========================================

// Configure 3-phase timer

//==========================================

//PRC1 in PRCR should be set before

invc0 = 0x1C;

// Bit 0-1 - 00

// Bit 2 - Three phase timers enable = 1

// Bit 3 - Enable output = 1

// Bit 4 - Simulataneous Conduction protection = 1

// Bit 5 - SC detection (Read only) = 0

// Bit 6 - Pwm mode = 0 (Triangle)

// Bit 7 - Software trigger ? =test setting to 0

// Bit 0 - When to reload = 0 (only when tb2 reloads)

// Bit 1 - Three phase mode = 0

// Bit 2 - Dead time counter clk source = 0 (f1=24M)

// Bit 3 - Carrier wave detection flag = 0(Read Only)

// Bit 4 - Active level control bit = 1 (active high output)

// Bit 5 - Dead time disable = 0 (Enable)

// Bit 6 - Dead time trigger = 1

// Bit 7 - 0

//==========================================

// Set PRCR register - WR disable

//==========================================

prcr = 0x00;

//==========================================

// TB2 Settings

//==========================================

tb2sc = 0x00;

//Bit 0 - Set reload options for B2 timer = 0 (PWMCON = 0)

//Which should be used?

idb0 = 0x3B;

// Bit 2 - Enable V shift registers = 0 (Active)

// Bit 6 and 7 = 0

// Bit 3 - Enable V^ shift registers = 0 (Active)

// Bit 6 and 7 = 0

//==========================================

// Configure Timer TA1 and TB2

//==========================================

//Bit 0-1 - Timer mode = 10 (One shot)

//Bit 4 - Trigger Select = 1 (Three phase)

//Bit 0-1 - Operating mode bit = 00

//Bit 2-5 - MR0-3 = 0000

//Bit 6-7 - CLK select = 00 (f1=24MHz)

//Bit 0-1 - Trigger on V-phase = 01(?)

//==========================================

// Configure pwm counter timer TB2

//==========================================

tb2 = 750;

//PWM Freq = f1 / (tb2*2) = 24 /1500 = 16kHZ

// Timer B2 interrupt priority level 7

//===========================================

// Dead time counter

//===========================================

//TODO: kolla med Magnus vad som kan vara

vettigt

//Simultaneous conduction protection is enabled

dtt = 10;

//Dead time counter 10x41,6 ns approx 400 ns; //TODO: Check

//===========================================

// PWM Register

//===========================================

ta1 = pwm_pwmValue;

//PWM

//==========================================

// Output settings

//==========================================

//Disable register protect

iobc = 0x00;

//Bit 7 - Three phase output pin setting = 0 (use port p7

prcr = 0x00;

//Enable register protect

//==========================================

// Pin setting

//==========================================

p7_2s = 0x02;

// V

p7_3s = 0x02;

// V(Negative phase)s

pd7_2 = 1;

pd7_3 = 1;

//Enable IRQ

asm("FSET I"); //TODO Use macro

//===========================================

// Start timer B2

// (TA1 is started automatically)

//===========================================

tabsr = 0x82;

//Bit 1 - Set A1 Counter to sample input

//Bit 7 - Set TB2S bit to 1 to start timer

}