diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/stm32f4/Kconfig | 1 | ||||
| -rw-r--r-- | src/stm32f4/Makefile | 1 | ||||
| -rw-r--r-- | src/stm32f4/adc.c | 89 | ||||
| -rw-r--r-- | src/stm32f4/gpio.h | 8 |
4 files changed, 99 insertions, 0 deletions
diff --git a/src/stm32f4/Kconfig b/src/stm32f4/Kconfig index df22d36c..df2036ab 100644 --- a/src/stm32f4/Kconfig +++ b/src/stm32f4/Kconfig @@ -6,6 +6,7 @@ config STM32F4_SELECT bool default y select HAVE_GPIO + select HAVE_GPIO_ADC config BOARD_DIRECTORY string diff --git a/src/stm32f4/Makefile b/src/stm32f4/Makefile index 6ed6a52b..b1c22cb7 100644 --- a/src/stm32f4/Makefile +++ b/src/stm32f4/Makefile @@ -15,6 +15,7 @@ src-y += stm32f4/main.c stm32f4/clock.c stm32f4/watchdog.c stm32f4/gpio.c src-y += generic/crc16_ccitt.c generic/alloc.c src-y += generic/armcm_irq.c generic/armcm_timer.c src-y += ../lib/stm32f4/system_stm32f4xx.c +src-$(CONFIG_HAVE_GPIO_ADC) += stm32f4/adc.c src-$(CONFIG_SERIAL) += stm32f4/serial.c generic/serial_irq.c # Add assembler build rules diff --git a/src/stm32f4/adc.c b/src/stm32f4/adc.c new file mode 100644 index 00000000..e112c2a0 --- /dev/null +++ b/src/stm32f4/adc.c @@ -0,0 +1,89 @@ +// ADC functions on STM32F4 +// +// Copyright (C) 2019 Kevin O'Connor <kevin@koconnor.net> +// +// This file may be distributed under the terms of the GNU GPLv3 license. + +#include "board/irq.h" // irq_save +#include "board/misc.h" // timer_from_us +#include "command.h" // shutdown +#include "compiler.h" // ARRAY_SIZE +#include "gpio.h" // gpio_adc_setup +#include "internal.h" // GPIO +#include "sched.h" // sched_shutdown + +DECL_CONSTANT("ADC_MAX", 4095); + +static const uint8_t adc_pins[] = { + GPIO('A', 0), GPIO('A', 1), GPIO('A', 2), GPIO('A', 3), + GPIO('A', 4), GPIO('A', 5), GPIO('A', 6), GPIO('A', 7), + GPIO('B', 0), GPIO('B', 1), GPIO('C', 0), GPIO('C', 1), + GPIO('C', 2), GPIO('C', 3), GPIO('C', 4), GPIO('C', 5) +}; + +struct gpio_adc +gpio_adc_setup(uint32_t pin) +{ + // Find pin in adc_pins table + int chan; + for (chan=0; ; chan++) { + if (chan >= ARRAY_SIZE(adc_pins)) + shutdown("Not a valid ADC pin"); + if (adc_pins[chan] == pin) + break; + } + + // Enable the ADC + enable_pclock(ADC1_BASE); + uint32_t aticks = 3; // 56 adc cycles + ADC1->SMPR1 = (aticks | (aticks << 3) | (aticks << 6) | (aticks << 9) + | (aticks << 12) | (aticks << 15) | (aticks << 18) + | (aticks << 21) | (aticks << 24)); + ADC1->SMPR2 = (aticks | (aticks << 3) | (aticks << 6) | (aticks << 9) + | (aticks << 12) | (aticks << 15) | (aticks << 18) + | (aticks << 21) | (aticks << 24) | (aticks << 27)); + ADC1->CR2 = ADC_CR2_ADON; + + gpio_peripheral(pin, GPIO_ANALOG, 0, 0); + + return (struct gpio_adc){ .chan = chan }; +} + +// Try to sample a value. Returns zero if sample ready, otherwise +// returns the number of clock ticks the caller should wait before +// retrying this function. +uint32_t +gpio_adc_sample(struct gpio_adc g) +{ + uint32_t sr = ADC1->SR; + if (sr & ADC_SR_STRT) { + if (!(sr & ADC_SR_EOC) || ADC1->SQR3 != g.chan) + // Conversion still in progress or busy on another channel + goto need_delay; + // Conversion ready + return 0; + } + // Start sample + ADC1->SQR3 = g.chan; + ADC1->CR2 = ADC_CR2_SWSTART | ADC_CR2_ADON; +need_delay: + return timer_from_us(4); +} + +// Read a value; use only after gpio_adc_sample() returns zero +uint16_t +gpio_adc_read(struct gpio_adc g) +{ + ADC1->SR = ~ADC_SR_STRT; + return ADC1->DR; +} + +// Cancel a sample that may have been started with gpio_adc_sample() +void +gpio_adc_cancel_sample(struct gpio_adc g) +{ + irqstatus_t flag = irq_save(); + if (ADC1->SR & ADC_SR_STRT && ADC1->SQR3 == g.chan) + gpio_adc_read(g); + irq_restore(flag); +} diff --git a/src/stm32f4/gpio.h b/src/stm32f4/gpio.h index 025b30e1..6aaf02c3 100644 --- a/src/stm32f4/gpio.h +++ b/src/stm32f4/gpio.h @@ -21,4 +21,12 @@ struct gpio_in gpio_in_setup(uint32_t pin, int32_t pull_up); void gpio_in_reset(struct gpio_in g, int32_t pull_up); uint8_t gpio_in_read(struct gpio_in g); +struct gpio_adc { + uint32_t chan; +}; +struct gpio_adc gpio_adc_setup(uint32_t pin); +uint32_t gpio_adc_sample(struct gpio_adc g); +uint16_t gpio_adc_read(struct gpio_adc g); +void gpio_adc_cancel_sample(struct gpio_adc g); + #endif // gpio.h |