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/*
* Copyright © 2019 Keith Packard <keithp@keithp.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*/
#include "ao.h"
#include "ao_max6691.h"
#include "ao_exti.h"
#define cat2(a,b) a ## b
#define cat(a,b) cat2(a,b)
#if AO_MAX6691_CH != 2
#error ao_max6691 driver currently only works for timer channel 2
#endif
#define AO_MAX6691_CCR (AO_MAX6691_TIMER->cat(ccr, AO_MAX6691_CH))
/* Two samples per channel, plus time start value and two for Tready pulse */
#define AO_MAX6691_SAMPLES (AO_MAX6691_CHANNELS * 2 + 3)
static uint16_t ao_max6691_raw[AO_MAX6691_SAMPLES];
static inline uint16_t
ao_max6691_t_high(int channel)
{
return ao_max6691_raw[channel * 2 + 3] - ao_max6691_raw[channel * 2 + 2];
}
static inline uint16_t
ao_max6691_t_low(int channel)
{
return ao_max6691_raw[channel * 2 + 4] - ao_max6691_raw[channel * 2 + 3];
}
void
ao_max6691_sample(struct ao_max6691 *ao_max6691)
{
struct stm_tim234 *tim = AO_MAX6691_TIMER;
tim->sr = 0;
memset(&ao_max6691_raw, '\0', sizeof (ao_max6691_raw));
/* Get the DMA engine ready */
ao_dma_set_transfer(AO_MAX6691_DMA,
&AO_MAX6691_CCR,
&ao_max6691_raw,
AO_MAX6691_SAMPLES,
(0 << STM_DMA_CCR_MEM2MEM) |
(STM_DMA_CCR_PL_MEDIUM << STM_DMA_CCR_PL) |
(STM_DMA_CCR_MSIZE_16 << STM_DMA_CCR_MSIZE) |
(STM_DMA_CCR_PSIZE_16 << STM_DMA_CCR_PSIZE) |
(1 << STM_DMA_CCR_MINC) |
(0 << STM_DMA_CCR_PINC) |
(0 << STM_DMA_CCR_CIRC) |
(STM_DMA_CCR_DIR_PER_TO_MEM << STM_DMA_CCR_DIR));
ao_dma_start(AO_MAX6691_DMA);
/* Prod the max6691 */
ao_set_output(AO_MAX6691_GPIO, AO_MAX6691_PIN, 0);
int i;
for (i = 0; i < 100; i++)
ao_arch_nop();
ao_set_input(AO_MAX6691_GPIO, AO_MAX6691_PIN);
for (i = 0; i < 100; i++)
ao_arch_nop();
/* Reset the timer count */
tim->cnt = 0;
/* Switch the pin to timer input mode */
stm_afr_set(AO_MAX6691_GPIO, AO_MAX6691_PIN, STM_AFR_AF1);
tim->ccer = ((0 << STM_TIM234_CCER_CC1E) |
(0 << STM_TIM234_CCER_CC1P) |
(0 << STM_TIM234_CCER_CC1NP) |
(1 << STM_TIM234_CCER_CC2E) |
(1 << STM_TIM234_CCER_CC2P) |
(1 << STM_TIM234_CCER_CC2NP) |
(0 << STM_TIM234_CCER_CC3E) |
(0 << STM_TIM234_CCER_CC3P) |
(0 << STM_TIM234_CCER_CC3NP) |
(0 << STM_TIM234_CCER_CC4E) |
(0 << STM_TIM234_CCER_CC4P) |
(0 << STM_TIM234_CCER_CC4NP));
/* Enable event generation on channel 2 */
tim->egr = ((0 << STM_TIM234_EGR_TG) |
(0 << STM_TIM234_EGR_CC4G) |
(0 << STM_TIM234_EGR_CC3G) |
(1 << STM_TIM234_EGR_CC2G) |
(0 << STM_TIM234_EGR_CC1G) |
(0 << STM_TIM234_EGR_UG));
/* Start the timer */
tim->cr1 |= (1 << STM_TIM234_CR1_CEN);
ao_arch_block_interrupts();
while (!ao_dma_done[AO_MAX6691_DMA])
ao_sleep(&ao_dma_done[AO_MAX6691_DMA]);
ao_arch_release_interrupts();
/* Disable event generation */
tim->egr = 0;
/* Disable capture */
tim->ccer = 0;
/* Stop the timer */
tim->cr1 &= ~(1 << STM_TIM234_CR1_CEN);
/* Switch back to GPIO mode */
stm_moder_set(AO_MAX6691_GPIO, AO_MAX6691_PIN, STM_MODER_INPUT);
/* Mark DMA done */
ao_dma_done_transfer(AO_MAX6691_DMA);
for (i = 0; i < AO_MAX6691_CHANNELS; i++) {
ao_max6691->sensor[i].t_high = ao_max6691_t_high(i);
ao_max6691->sensor[i].t_low = ao_max6691_t_low(i);
}
}
#define R_EXT 1000.0f
static void
ao_max6691_test(void)
{
struct ao_max6691 ao_max6691;
printf("Testing MAX6691\n"); flush();
ao_max6691_sample(&ao_max6691);
int i;
for (i = 0; i < AO_MAX6691_SAMPLES; i++)
printf("%d: %5u\n", i, ao_max6691_raw[i]);
for (i = 0; i < AO_MAX6691_CHANNELS; i++) {
uint16_t t_high = ao_max6691.sensor[i].t_high;
uint16_t t_low = ao_max6691.sensor[i].t_low;
/*
* From the MAX6691 data sheet
*
* Thigh Vext Rext
* ----- = ---- - 0.0002 = ---------- - 0.0002
* Tlow Vref Rext - Rth
*
* We want to find Rth given Rext and the timing values
*
* Thigh Rext
* ----- + 0.0002 = ----------
* Tlow Rext + Rth
*
* V = (Thigh / Tlow + 0.0002)
*
* (Rext + Rth) * V = Rext
*
* Rext * V + Rth * V = Rext
*
* Rth * V = Rext - Rext * V
*
* Rth * V = Rext * (1 - V)
*
* Rth = Rext * (1 - V) / V
*/
float V = (float) t_high / (float) t_low + 0.0002f;
float Rth = R_EXT * (1 - V) / V;
printf("%d: high %5u low %5u ohms: %7g\n", i, t_high, t_low, Rth);
}
}
static const struct ao_cmds ao_max6691_cmds[] = {
{ ao_max6691_test, "q\0Thermistor test" },
{ 0, NULL },
};
void
ao_max6691_init(void)
{
ao_cmd_register(&ao_max6691_cmds[0]);
struct stm_tim234 *tim = AO_MAX6691_TIMER;
stm_rcc.apb1enr |= (1 << AO_MAX6691_TIMER_ENABLE);
tim->cr1 = 0;
tim->psc = (AO_TIM23467_CLK / 4000000) - 1; /* run the timer at 4MHz */
tim->cnt = 0;
/*
* XXX This assumes we're using CH2, which is true on TeleFireOne v2.0
*/
tim->ccmr1 = ((STM_TIM234_CCMR1_IC2F_NONE << STM_TIM234_CCMR1_IC2F) |
(STM_TIM234_CCMR1_IC2PSC_NONE << STM_TIM234_CCMR1_IC2PSC) |
(STM_TIM234_CCMR1_CC2S_INPUT_TI2 << STM_TIM234_CCMR1_CC2S));
tim->ccer = 0;
tim->sr = 0;
tim->dier = 0;
tim->smcr = 0;
tim->cr2 = ((0 << STM_TIM234_CR2_TI1S) |
(STM_TIM234_CR2_MMS_RESET<< STM_TIM234_CR2_MMS) |
(0 << STM_TIM234_CR2_CCDS));
tim->dier = ((0 << STM_TIM234_DIER_TDE) |
(0 << STM_TIM234_DIER_CC4DE) |
(0 << STM_TIM234_DIER_CC3DE) |
(1 << STM_TIM234_DIER_CC2DE) |
(0 << STM_TIM234_DIER_CC1DE) |
(0 << STM_TIM234_DIER_TIE) |
(0 << STM_TIM234_DIER_CC4IE) |
(0 << STM_TIM234_DIER_CC3IE) |
(0 << STM_TIM234_DIER_CC2IE) |
(0 << STM_TIM234_DIER_CC1IE) |
(0 << STM_TIM234_DIER_UIE));
tim->egr = 0;
tim->cr1 = ((STM_TIM234_CR1_CKD_1 << STM_TIM234_CR1_CKD) |
(0 << STM_TIM234_CR1_ARPE) |
(STM_TIM234_CR1_CMS_EDGE << STM_TIM234_CR1_CMS) |
(STM_TIM234_CR1_DIR_UP << STM_TIM234_CR1_DIR) |
(0 << STM_TIM234_CR1_OPM) |
(0 << STM_TIM234_CR1_URS) |
(0 << STM_TIM234_CR1_UDIS) |
(0 << STM_TIM234_CR1_CEN));
stm_ospeedr_set(AO_MAX6691_GPIO, AO_MAX6691_PIN, STM_OSPEEDR_40MHz);
ao_enable_input(AO_MAX6691_GPIO, AO_MAX6691_PIN, AO_EXTI_MODE_PULL_UP);
}
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