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Use 10-bit ADC value for pin strap detection

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Previously we thought we were configuring the ADC for 8-bit values, but
we did so incorrectly. We were throwing away the top two bits of a
10-bit value. This never caused a problem because the only fixed
voltages we used were at the extreme minimum or maximum of the ADC
range.
This commit is contained in:
Michael Ossmann
2024-02-21 23:29:27 -05:00
parent 4b036648fd
commit 93d9f9b45c
1 changed files with 6 additions and 4 deletions
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10
firmware/common/platform_detect.c
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@ -60,12 +60,14 @@ static struct gpio_t gpio_led1 = GPIO(2, 1);
static struct gpio_t gpio_led2 = GPIO(2, 2);
static struct gpio_t gpio_led3 = GPIO(2, 8);
uint8_t adc_read(uint8_t pin)
/*
* Return 10-bit ADC result.
*/
uint16_t adc_read(uint8_t pin)
{
pin &= 0x7;
uint8_t pin_mask = (1 << pin);
ADC0_CR = ADC_CR_SEL(pin_mask) | ADC_CR_CLKDIV(45) | ADC_CR_CLKS(2) | ADC_CR_PDN |
ADC_CR_START(1);
ADC0_CR = ADC_CR_SEL(pin_mask) | ADC_CR_CLKDIV(45) | ADC_CR_PDN | ADC_CR_START(1);
while (!(ADC0_GDR & ADC_DR_DONE) || (((ADC0_GDR >> 24) & 0x7) != pin)) {}
return (ADC0_GDR >> 6) & 0x03FF;
}
@ -82,7 +84,7 @@ void adc_off(void)
*/
#define NUM_SAMPLES (10)
#define LOW_THRESHOLD (2 * NUM_SAMPLES)
#define HIGH_THRESHOLD (253 * NUM_SAMPLES)
#define HIGH_THRESHOLD (1022 * NUM_SAMPLES)
typedef enum {
PIN_STRAP_HIGH,