diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/lpc176x/Kconfig | 1 | ||||
| -rw-r--r-- | src/lpc176x/gpio.c | 91 | ||||
| -rw-r--r-- | src/lpc176x/gpio.h | 8 |
3 files changed, 100 insertions, 0 deletions
diff --git a/src/lpc176x/Kconfig b/src/lpc176x/Kconfig index df2343ad..cdfad6cd 100644 --- a/src/lpc176x/Kconfig +++ b/src/lpc176x/Kconfig @@ -6,6 +6,7 @@ config LPC_SELECT bool default y select HAVE_GPIO + select HAVE_GPIO_ADC config BOARD_DIRECTORY string diff --git a/src/lpc176x/gpio.c b/src/lpc176x/gpio.c index 8688ee75..e36c2860 100644 --- a/src/lpc176x/gpio.c +++ b/src/lpc176x/gpio.c @@ -5,7 +5,9 @@ // This file may be distributed under the terms of the GNU GPLv3 license. #include "LPC17xx.h" // LPC_PINCON +#include "autoconf.h" // CONFIG_CLOCK_FREQ #include "board/irq.h" // irq_save +#include "board/misc.h" // timer_from_us #include "command.h" // shutdown #include "gpio.h" // gpio_out_setup #include "internal.h" // gpio_peripheral @@ -117,3 +119,92 @@ gpio_in_read(struct gpio_in g) LPC_GPIO_TypeDef *regs = g.regs; return !!(regs->FIOPIN & g.bit); } + + +/**************************************************************** + * Analog to Digital Converter (ADC) pins + ****************************************************************/ + +static const uint8_t adc_pins[] = { + GPIO(0, 23), GPIO(0, 24), GPIO(0, 25), GPIO(0, 26), + GPIO(1, 30), GPIO(1, 31), GPIO(0, 3), GPIO(0, 2), +}; + +static const uint8_t adc_pin_funcs[] = { + 1, 1, 1, 1, 3, 3, 2, 2 +}; + +#define ADC_FREQ_MAX 13000000 +DECL_CONSTANT(ADC_MAX, 4095); + +struct gpio_adc +gpio_adc_setup(uint8_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; + } + + uint32_t prescal = DIV_ROUND_UP(CONFIG_CLOCK_FREQ*4, ADC_FREQ_MAX) - 1; + uint32_t adcr = (1<<21) | ((prescal & 0xff) << 8); + if (!(LPC_SC->PCONP & (1<<12))) { + // Power up ADC + LPC_SC->PCONP |= 1<<12; + LPC_SC->PCLKSEL0 = (LPC_SC->PCLKSEL0 & ~(0x3<<24)) | (0x1<<24); + LPC_ADC->ADCR = adcr; + } + + gpio_peripheral(GPIO2PORT(pin), pin % 32, adc_pin_funcs[chan], 0); + + return (struct gpio_adc){ .cmd = adcr | (1 << chan) | (1 << 24) }; +} + +static uint32_t adc_status; + +// 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 status = adc_status; + if (status == g.cmd) { + // Sample already underway - check if it is ready + uint32_t val = LPC_ADC->ADGDR; + if (val & (1<<31)) + // Sample ready + return 0; + goto need_delay; + } + if (status) + // ADC busy on some other channel + goto need_delay; + + // Start new sample + adc_status = g.cmd; + LPC_ADC->ADCR = g.cmd; + +need_delay: + return (65 * DIV_ROUND_UP(CONFIG_CLOCK_FREQ*4, ADC_FREQ_MAX) + + timer_from_us(10)); +} + +// Read a value; use only after gpio_adc_sample() returns zero +uint16_t +gpio_adc_read(struct gpio_adc g) +{ + adc_status = 0; + return (LPC_ADC->ADGDR >> 4) & 0x0fff; +} + +// Cancel a sample that may have been started with gpio_adc_sample() +void +gpio_adc_cancel_sample(struct gpio_adc g) +{ + if (adc_status == g.cmd) + adc_status = 0; +} diff --git a/src/lpc176x/gpio.h b/src/lpc176x/gpio.h index 030528e6..79a84823 100644 --- a/src/lpc176x/gpio.h +++ b/src/lpc176x/gpio.h @@ -19,4 +19,12 @@ struct gpio_in { struct gpio_in gpio_in_setup(uint8_t pin, int8_t pull_up); uint8_t gpio_in_read(struct gpio_in g); +struct gpio_adc { + uint32_t cmd; +}; +struct gpio_adc gpio_adc_setup(uint8_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 |