dali/bacnet_stack
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
Files
fe2c7cd00a8155c8f153d3b07211fa2d81df19f2
bacnet_stack/bacnet-stack/ports/at91sam7s/timer.c
T

363 lines
14 KiB
C
Raw Blame History

// *****************************************************************************
//
// Purpose: Set up the 16-bit Timer/Counter
//
// We will use Timer Channel 0 to develop a 1 msec interrupt.
//
// The AT91SAM7S-EK board has a 18,432,000 hz crystal oscillator.
//
// MAINCK = 18432000 hz
// PLLCK = (MAINCK / DIV) * (MUL + 1) = 18432000/14 * (72 + 1)
// PLLCLK = 1316571 * 73 = 96109683 hz
//
// MCK = PLLCLK / 2 = 96109683 / 2 = 48054841 hz
//
// TIMER_CLOCK5 = MCK / 1024 = 48054841 / 1024 = 46928 hz
//
// TIMER_CLOCK5 Period = 1 / 46928 = 21.309239686 microseconds
//
// A little algebra: .001 sec = count * 21.3092396896*10**-6
// count = .001 / 21.3092396896*10**-6
// count = 46.928
//
//
// Therefore: set Timer Channel 0 register RC to 46*milliseconds
// turn on capture mode WAVE = 0
// enable the clock CLKEN = 1
// select TIMER_CLOCK5 TCCLKS = 100
// clock is NOT inverted CLKI = 0
// enable RC compare CPCTRG = 1
// enable RC compare interrupt CPCS = 1
// disable all the other timer 0 interrupts
//
// Author: James P Lynch May 12, 2007
// Modified by Steve Karg
// Changed timer to 1ms.
// Encapsulated the intialization
// *****************************************************************************
/**********************************************************
Header files
**********************************************************/
#include <stdint.h>
#include "AT91SAM7S256.h"
#include "board.h"
#include "dlmstp.h"
/* global variable counts interrupts */
volatile unsigned long Timer_Milliseconds;
/* MS/TP Silence Timer */
static volatile int SilenceTime;
static void Timer0_Setup(int milliseconds) {
// TC Block Control Register TC_BCR (read/write)
//
// |------------------------------------------------------------------|------|
// | SYNC |
// |------------------------------------------------------------------|------|
// 31 1 0
//
// SYNC = 0 (no effect) <===== take default
// SYNC = 1 (generate software trigger for all 3 timer channels simultaneously)
//
// create a pointer to TC Global Register structure
AT91PS_TCB pTCB = AT91C_BASE_TCB;
// SYNC trigger not used
pTCB->TCB_BCR = 0;
// TC Block Mode Register TC_BMR (read/write)
//
// |-------------------------------------|-----------|-----------|-----------|
// | TC2XC2S TCXC1S TC0XC0S |
// |-------------------------------------|-----------|-----------|-----------|
// 31 5 4 3 2 1 0
//
// TC0XC0S Select = 00 TCLK0 (PA4)
// = 01 none <===== we select this one
// = 10 TIOA1 (PA15)
// = 11 TIOA2 (PA26)
//
// TCXC1S Select = 00 TCLK1 (PA28)
// = 01 none <===== we select this one
// = 10 TIOA0 (PA15)
// = 11 TIOA2 (PA26)
//
// TC2XC2S Select = 00 TCLK2 (PA29)
// = 01 none <===== we select this one
// = 10 TIOA0 (PA00)
// = 11 TIOA1 (PA26)
//
// external clocks not used
pTCB->TCB_BMR = 0x15;
// TC Channel Control Register TC_CCR (read/write)
//
// |----------------------------------|--------------|------------|-----------|
// | SWTRG CLKDIS CLKENS |
// |----------------------------------|--------------|------------|-----------|
// 31 2 1 0
//
// CLKEN = 0 no effect
// CLKEN = 1 enables the clock <===== we select this one
//
// CLKDIS = 0 no effect <===== take default
// CLKDIS = 1 disables the clock
//
// SWTRG = 0 no effect
// SWTRG = 1 software trigger aserted counter reset and clock starts <===== we select this one
//
// create a pointer to channel 0 Register structure
AT91PS_TC pTC = AT91C_BASE_TC0;
// enable the clock and start it
pTC->TC_CCR = 0x5;
// TC Channel Mode Register TC_CMR (read/write)
//
// |-----------------------------------|------------|---------------|
// | LDRB LDRA |
// |-----------------------------------|------------|---------------|
// 31 19 18 17 16
//
// |----------|---------|--------------|------------|---------------|
// |WAVE = 0 CPCTRG ABETRG ETRGEDG |
// |----------|---------|--------------|------------|---------------|
// 15 14 13 11 10 9 8
//
// |----------|---------|--------------|------------|---------------|
// | LDBDIS LDBSTOP BURST CLKI TCCLKS |
// |----------|---------|--------------|------------|---------------|
// 7 6 5 4 3 2 0
//
// CLOCK SELECTION
// TCCLKS = 000 TIMER_CLOCK1 (MCK/2 = 24027420 hz)
// 001 TIMER_CLOCK2 (MCK/8 = 6006855 hz)
// 010 TIMER_CLOCK3 (MCK/32 = 1501713 hz)
// 011 TIMER_CLOCK4 (MCK/128 = 375428 hz)
// 100 TIMER_CLOCK5 (MCK/1024 = 46928 hz) <===== we select this one
// 101 XC0
// 101 XC1
// 101 XC2
//
// CLOCK INVERT
// CLKI = 0 counter incremented on rising clock edge <===== we select this one
// CLKI = 1 counter incremented on falling clock edge
//
// BURST SIGNAL SELECTION
// BURST = 00 clock is not gated by any external system <===== take default
// 01 XC0 is anded with the clock
// 10 XC1 is anded with the clock
// 11 XC2 is anded with the clock
//
// COUNTER CLOCK STOPPED WITH RB LOADING
// LDBSTOP = 0 counter clock is not stopped when RB loading occurs <===== take default
// = 1 counter clock is stopped when RB loading occur
//
// COUNTER CLOCK DISABLE WITH RB LOADING
// LDBDIS = 0 counter clock is not disabled when RB loading occurs <===== take default
// = 1 counter clock is disabled when RB loading occurs
//
// EXTERNAL TRIGGER EDGE SELECTION
// ETRGEDG = 00 (none) <===== take default
// 01 (rising edge)
// 10 (falling edge)
// 11 (each edge)
//
// TIOA OR TIOB EXTERNAL TRIGGER SELECTION
// ABETRG = 0 (TIOA is used) <===== take default
// 1 (TIOB is used)
//
// RC COMPARE TRIGGER ENABLE
// CPCTRG = 0 (RC Compare has no effect on the counter and its clock)
// 1 (RC Compare resets the counter and starts the clock) <===== we select this one
//
// WAVE
// WAVE = 0 Capture Mode is enabled <===== we select this one
// 1 Waveform Mode is enabled
//
// RA LOADING SELECTION
// LDRA = 00 none) <===== take default
// 01 (rising edge of TIOA)
// 10 (falling edge of TIOA)
// 11 (each edge of TIOA)
//
// RB LOADING SELECTION
// LDRB = 00 (none) <===== take default
// 01 (rising edge of TIOA)
// 10 (falling edge of TIOA)
// 11 (each edge of TIOA)
//
// TCCLKS = 1 (TIMER_CLOCK5)
// CPCTRG = 1 (RC Compare resets the counter and restarts the clock)
// WAVE = 0 (Capture mode enabled)
pTC->TC_CMR = 0x4004;
// TC Register C TC_RC (read/write) Compare Register 16-bits
//
// |----------------------------------|----------------------------------------|
// | not used RC |
// |----------------------------------|----------------------------------------|
// 31 16 15 0
//
// Timer Calculation: What count gives 1 msec time-out?
//
// TIMER_CLOCK5 = MCK / 1024 = 48054841 / 1024 = 46928 hz
//
// TIMER_CLOCK5 Period = 1 / 46928 = 21.309239686 microseconds
//
// A little algebra: .001 sec = count * 21.3092396896*10**-6
// count = .001 / 21.3092396896*10**-6
// count = 46.928
//
// STK: Even Simpler, let the compiler do the work:
//
// TIMER_CLOCK5 = (MCK / 1024) / 1000
// = 48054841 / 1024 / 1000 = 46.928
pTC->TC_RC = ((MCK/1024/1000)+1)*milliseconds;
// TC Interrupt Enable Register TC_IER (write-only)
//
//
// |------------|-------|-------|-------|-------|--------|--------|--------|--------|
// | ETRGS LDRBS LDRAS CPCS CPBS CPAS LOVRS COVFS |
// |------------|-------|-------|-------|-------|--------|--------|--------|--------|
// 31 8 7 6 5 4 3 2 1 0
//
// COVFS = 0 no effect <===== take default
// 1 enable counter overflow interrupt
//
// LOVRS = 0 no effect <===== take default
// 1 enable load overrun interrupt
//
// CPAS = 0 no effect <===== take default
// 1 enable RA compare interrupt
//
// CPBS = 0 no effect <===== take default
// 1 enable RB compare interrupt
//
// CPCS = 0 no effect
// 1 enable RC compare interrupt <===== we select this one
//
// LDRAS = 0 no effect <===== take default
// 1 enable RA load interrupt
//
// LDRBS = 0 no effect <===== take default
// 1 enable RB load interrupt
//
// ETRGS = 0 no effect <===== take default
// 1 enable External Trigger interrupt
//
// enable RC compare interrupt
pTC->TC_IER = 0x10;
// TC Interrupt Disable Register TC_IDR (write-only)
//
//
// |------------|-------|-------|-------|-------|--------|--------|--------|--------|
// | ETRGS LDRBS LDRAS CPCS CPBS CPAS LOVRS COVFS |
// |------------|-------|-------|-------|-------|--------|--------|--------|--------|
// 31 8 7 6 5 4 3 2 1 0
//
// COVFS = 0 no effect
// 1 disable counter overflow interrupt <===== we select this one
//
// LOVRS = 0 no effect
// 1 disable load overrun interrupt <===== we select this one
//
// CPAS = 0 no effect
// 1 disable RA compare interrupt <===== we select this one
//
// CPBS = 0 no effect
// 1 disable RB compare interrupt <===== we select this one
//
// CPCS = 0 no effect <===== take default
// 1 disable RC compare interrupt
//
// LDRAS = 0 no effect
// 1 disable RA load interrupt <===== we select this one
//
// LDRBS = 0 no effect
// 1 disable RB load interrupt <===== we select this one
//
// ETRGS = 0 no effect
// 1 disable External Trigger interrupt <===== we select this one
//
// disable all except RC compare interrupt
pTC->TC_IDR = 0xEF;
}
// *****************************************************************************
//
// Timer 0 Interrupt Service Routine
//
// Entered when Timer0 RC compare interrupt asserts
//
// Author: James P Lynch May 12, 2007
// Modified by Steve Karg
// simplified and changed to a millisecond count-up timer
// *****************************************************************************
static void Timer0IrqHandler (void) {
volatile AT91PS_TC pTC = AT91C_BASE_TC0; // pointer to timer channel 0 register structure
unsigned int dummy; // temporary
// read TC0 Status Register to clear interrupt
dummy = pTC->TC_SR;
// increment the tick count
Timer_Milliseconds++;
if (SilenceTime < 60000)
SilenceTime++;
}
int Timer_Silence(void)
{
return SilenceTime;
}
void Timer_Silence_Reset(void)
{
SilenceTime = 0;
}
// *****************************************************************************
//
// Timer 0 Initialization
//
// From James P Lynch main.c example code
// Modified by Steve Karg
// Moved timer startup code from main
// modified the peripheral clock init
// *****************************************************************************
void TimerInit(void)
{
// enable the Timer0 peripheral clock
volatile AT91PS_PMC pPMC = AT91C_BASE_PMC;
pPMC->PMC_PCER = pPMC->PMC_PCSR | (1<<AT91C_ID_TC0);
// Set up the AIC registers for Timer 0
volatile AT91PS_AIC pAIC = AT91C_BASE_AIC;
// Disable timer 0 interrupt
// in AIC Interrupt Disable Command Register
pAIC->AIC_IDCR = (1<<AT91C_ID_TC0);
// Set the TC0 IRQ handler address in
// AIC Source Vector Register[12]
pAIC->AIC_SVR[AT91C_ID_TC0] =
(unsigned int)Timer0IrqHandler;
// Set the interrupt source type and priority
// in AIC Source Mode Register[12]
pAIC->AIC_SMR[AT91C_ID_TC0] =
(AT91C_AIC_SRCTYPE_INT_LEVEL_SENSITIVE | 0x4 );
// Clear the TC0 interrupt
// in AIC Interrupt Clear Command Register
pAIC->AIC_ICCR = (1<<AT91C_ID_TC0);
// Remove disable timer 0 interrupt
// in AIC Interrupt Disable Command Reg
pAIC->AIC_IDCR = (0<<AT91C_ID_TC0);
// Enable the TC0 interrupt
// in AIC Interrupt Enable Command Register
pAIC->AIC_IECR = (1<<AT91C_ID_TC0);
// Setup timer0 to generate a 1 msec periodic interrupt
Timer0_Setup(1);
}
Reference in New Issue View Git Blame Copy Permalink