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[LPC1549] Improve AnalogIn Performance 

Modified the LPC1549 AnalogIn implementation to use the ADCs in
synchronous mode, which is consistent with the LPC11U68 implementation.
This improves performance, and allows the IRC oscillator to be powered
down if necessary.
pull/1564/head
neilt6 2016-02-24 14:07:09 -07:00
parent 8081c39aba
commit 6525b8ee3e
1 changed files with 2 additions and 6 deletions
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8
libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC15XX/analogin_api.c
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@ -77,10 +77,6 @@ void analogin_init(analogin_t *obj, PinName pin) {
LPC_SYSCON->SYSAHBCLKCTRL0 |= (1 << 28);
}
// select IRC as asynchronous clock, divided by 1
LPC_SYSCON->ADCASYNCCLKSEL = 0;
LPC_SYSCON->ADCASYNCCLKDIV = 1;
__IO LPC_ADC0_Type *adc_reg = (obj->adc < ADC1_0) ? (__IO LPC_ADC0_Type*)(LPC_ADC0) : (__IO LPC_ADC0_Type*)(LPC_ADC1);
// determine the system clock divider for a 500kHz ADC clock during calibration
@ -90,8 +86,8 @@ void analogin_init(analogin_t *obj, PinName pin) {
adc_reg->CTRL = (1UL << 30) | (clkdiv & 0xFF);
while ((adc_reg->CTRL & (1UL << 30)) != 0);
// switch to asynchronous mode
adc_reg->CTRL = (1UL << 8);
// Sampling clock: SystemClock divided by 1
adc_reg->CTRL = 0;
}
static inline uint32_t adc_read(analogin_t *obj) {