/
adc.c
114 lines (100 loc) · 2.96 KB
/
adc.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
#include <msp430.h>
#include <inttypes.h>
#include "adc.h"
#include "hw.h"
volatile uint16_t adc_result;
uint16_t adc_get_voltage(adc_voltage_channel channel) {
uint16_t i;
uint16_t voltage;
/* configure ADC
* * conversion clock ACLK = FDCO/32
* * FDCO/32 = 5.37 MHz/2 -> 370 ns period
* * worst case source impedance = 1 MOhm
* * input capacitance ~10 pF
* * ~80 us required sampling time
* * using 256 cycles for S&H is more than enough
* * max sample rate is ~13 kHz, so low speed mode can be used
*/
ADC10CTL0 = ADC10SHT_8 + ADC10ON;
ADC10CTL1 = ADC10SHP + ADC10SSEL0;
ADC10CTL2 = ADC10RES + ADC10SR;
switch (channel) {
case CHANNEL_VSOL:
ADC10MCTL0 = ADC_CHAN_VSOL;
break;
case CHANNEL_VBAT:
ADC10MCTL0 = ADC_CHAN_VBAT;
break;
}
ADC10IE = ADC10IE0;
/* take ADC reading */
voltage = 0;
for (i = 0; i < 10; i++) {
ADC10CTL0 |= ADC10ENC + ADC10SC;
__bis_SR_register(CPUOFF + GIE);
voltage += adc_result * 32 / 10;
}
voltage /= 10;
/* post process readings */
switch (channel) {
case CHANNEL_VBAT:
voltage = voltage * 2;
break;
default:
break;
}
/* disable ADC */
ADC10IE &= ~ADC10IE0;
ADC10CTL0 &= ~ADC10ENC;
ADC10CTL0 &= ~ADC10ON;
return voltage;
}
int16_t adc_get_temperature(void) {
long temperature;
/* configure ADC
* * 30 microsecond conversion time minimum
* * conversion clock ACLK = FDCO/2
* * FDCO/32 = 5.37 MHz/2 -> 370 ns period
* * ~30 us required sampling time
* * using 128 cycles for S&H is more than enough
* * max sample rate is ~13 kHz, so low speed mode can be used
*/
ADC10CTL0 = ADC10SHT_6 + ADC10ON;
ADC10CTL1 = ADC10SHP + ADC10SSEL0;
ADC10CTL2 = ADC10RES + ADC10SR;
ADC10MCTL0 = ADC10SREF_1 + ADC10INCH_10;
ADC10IE |= ADC10IE0;
/* Configure internal reference */
while(REFCTL0 & REFGENBUSY);
REFCTL0 |= REFVSEL_0 + REFON;
hw_delay_us(50);
/* take ADC reading */
ADC10CTL0 |= ADC10ENC + ADC10SC;
__bis_SR_register(CPUOFF + GIE);
temperature = adc_result;
temperature = (temperature - CALADC10_15V_30C) * (85-30) / (CALADC10_15V_85C-CALADC10_15V_30C) + 30;
/* disable ADC */
REFCTL0 &= ~REFON;
ADC10IE &= ~ADC10IE0;
ADC10CTL0 &= ~ADC10ENC;
ADC10CTL0 &= ~ADC10ON;
return temperature;
}
#pragma vector=ADC10_VECTOR
__interrupt void ADC10_ISR(void)
{
switch(ADC10IV)
{
case 0: break; // No interrupt
case 2: break; // conversion result overflow
case 4: break; // conversion time overflow
case 6: break; // ADC10HI
case 8: break; // ADC10LO
case 10: break; // ADC10IN
case 12:
adc_result = ADC10MEM0; // ADC10MEM0
__bic_SR_register_on_exit(CPUOFF);
break;
default: break;
}
}