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Add freq_ctr app

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The freq_ctr app is a small application that is implementing a
simplistic direct-mode frequency counter using the internal 32.768kHz
oscillator and two TC blocks. One of them is used to generate a 1Hz
signal, which is then subsequently used by the other TC to trigger
a counter read after exactly 1s.

This is in itself not something useful on a simtrace2 device.  However,
it is a separate 'app' and I prefer to have the code here in master
over some obscure branch that's easy to forget about.

Change-Id: I2249bfb8dd6a88d85d406f3b33537377133d0939
This commit is contained in:
Harald Welte
2019-02-28 18:24:36 +01:00
parent b7e326cad3
commit bb9b0dc8e8
4 changed files with 122 additions and 0 deletions
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55
firmware/apps/freq_ctr/freq_ctr.c Normal file
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#include <stdint.h>
#include "utils.h"
#include "tc_etu.h"
#include "chip.h"
/* pins for Channel 0 of TC-block 0 */
#define PIN_TIOA0 {PIO_PA0, PIOA, ID_PIOA, PIO_PERIPH_B, PIO_DEFAULT}
/* pins for Channel 1 of TC-block 0 */
#define PIN_TIOA1 {PIO_PA15, PIOA, ID_PIOA, PIO_PERIPH_B, PIO_DEFAULT}
#define PIN_TCLK1 {PIO_PA28, PIOA, ID_PIOA, PIO_PERIPH_B, PIO_DEFAULT}
static const Pin pins_tc[] = { PIN_TIOA0, PIN_TIOA1, PIN_TCLK1 };
static TcChannel *tc1 = &TC0->TC_CHANNEL[1];
void TC1_IrqHandler(void)
{
uint32_t sr = tc1->TC_SR;
printf("TC1=%lu; SR=0x%08lx\r\n", tc1->TC_RA, sr);
}
void freq_ctr_init(void)
{
TcChannel *tc0 = &TC0->TC_CHANNEL[0];
PIO_Configure(pins_tc, ARRAY_SIZE(pins_tc));
PMC_EnablePeripheral(ID_TC0);
PMC_EnablePeripheral(ID_TC1);
/* route TCLK1 to XC1 */
TC0->TC_BMR &= ~TC_BMR_TC1XC1S_Msk;
TC0->TC_BMR |= TC_BMR_TC1XC1S_TCLK1;
/* TC0 in wveform mode: Run from SCLK. Raise TIOA on RA; lower TIOA on RC + trigger */
tc0->TC_CMR = TC_CMR_TCCLKS_TIMER_CLOCK5 | TC_CMR_BURST_NONE |
TC_CMR_EEVTEDG_NONE | TC_CMR_WAVSEL_UP_RC | TC_CMR_WAVE |
TC_CMR_ACPA_SET | TC_CMR_ACPC_CLEAR;
tc0->TC_RA = 16384; /* set high at 16384 */
tc0->TC_RC = 32786; /* set low at 32786 */
/* TC1 in capture mode: Run from XC1. Trigger on TIOA rising. Load RA on rising */
tc1->TC_CMR = TC_CMR_TCCLKS_XC1 | TC_CMR_BURST_NONE |
TC_CMR_ETRGEDG_RISING | TC_CMR_ABETRG | TC_CMR_LDRA_RISING;
/* Interrupt us if the external trigger happens */
tc1->TC_IER = TC_IER_ETRGS;
NVIC_EnableIRQ(TC1_IRQn);
TC0->TC_BCR = TC_BCR_SYNC;
tc0->TC_CCR = TC_CCR_CLKEN|TC_CCR_SWTRG;
tc1->TC_CCR = TC_CCR_CLKEN|TC_CCR_SWTRG;
}