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Patch 772577 by Magnus Holmgren: measure all ADC channels within adc_init(), so afterwards adc_read() can be used right away.

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@3834 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Jörg Hohensohn 2003-07-16 21:07:53 +00:00
parent e9d40587de
commit d8a4bf3ec6
1 changed files with 37 additions and 2 deletions
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37
firmware/drivers/adc.c
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@ -48,10 +48,45 @@ unsigned short adc_read(int channel)
return adcdata[channel];
}
/* Batch convert 4 analog channels. If lower is true, convert AN0-AN3,
* otherwise AN4-AN7.
*/
static void adc_batch_convert(bool lower)
{
int reg = lower ? 0 : 4;
volatile unsigned short* ANx = ((unsigned short*) ADDRAH_ADDR);
int i;
ADCSR = ADCSR_ADST | ADCSR_SCAN | ADCSR_CKS | reg | 3;
/* Busy wait until conversion is complete. A bit ugly perhaps, but
* we should only need to wait about 4 * 14 µs */
while(!(ADCSR & ADCSR_ADF))
{
}
/* Stop scanning */
ADCSR = 0;
for (i = 0; i < 4; i++)
{
/* Read converted values */
adcdata[reg++] = ANx[i] >> 6;
}
}
void adc_init(void)
{
ADCR = 0; /* No external trigger */
int i;
ADCR = 0x7f; /* No external trigger; other bits should be 1 according to the manual... */
current_channel = 0;
/* Do a first scan to initialize all values */
/* AN0 to AN3 */
adc_batch_convert(true);
/* AN4 to AN7 */
adc_batch_convert(false);
tick_add_task(adc_tick);
}