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
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
|
/******************************************************************************
* The MIT License
*
* Copyright (c) 2010 Perry Hung.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*****************************************************************************/
/**
* @brief Analog to digital converter routines
*
* IMPORTANT: maximum external impedance must be below 0.4kOhms for 1.5
* sample conversion time.
*
* At 55.5 cycles/sample, the external input impedance < 50kOhms.
*
* See stm32 manual RM008 for how to calculate this.
*/
#include "libmaple.h"
#include "rcc.h"
#include "adc.h"
adc_dev adc1 = {
.regs = ADC1_BASE,
.clk_id = RCC_ADC1
};
const adc_dev *ADC1 = &adc1;
adc_dev adc2 = {
.regs = ADC2_BASE,
.clk_id = RCC_ADC2
};
const adc_dev *ADC2 = &adc2;
#ifdef STM32_HIGH_DENSITY
adc_dev adc3 = {
.regs = ADC3_BASE,
.clk_id = RCC_ADC3
};
const adc_dev *ADC3 = &adc3;
#endif
static void adc_calibrate(const adc_dev *dev);
/**
* @brief Initialize an ADC peripheral. Only supports software triggered
* conversions.
* @param dev ADC peripheral to initialize
* @param flags unused
*/
void adc_init(const adc_dev *dev, uint32 flags) {
/* Spin up the clocks */
rcc_set_prescaler(RCC_PRESCALER_ADC, RCC_ADCPRE_PCLK_DIV_6);
rcc_clk_enable(dev->clk_id);
rcc_reset_dev(dev->clk_id);
/* Software triggers conversions, conversion on external events */
adc_set_extsel(dev, 7);
adc_set_exttrig(dev, 1);
/* Enable the ADC */
adc_enable(dev);
/* Calibrate ADC */
adc_calibrate(dev);
}
/**
* @brief Set external event select for regular group
* @param dev adc device
* @param trigger event to select. See ADC_CR2 EXTSEL[2:0] bits.
*/
void adc_set_extsel(const adc_dev *dev, uint8 trigger) {
uint32 cr2 = dev->regs->CR2;
cr2 &= ~ADC_CR2_EXTSEL;
cr2 |= (trigger & 0x7) << 17;
dev->regs->CR2 = cr2;
}
/**
* @brief Turn the given sample rate into values for ADC_SMPRx. Don't
* call this during conversion.
* @param dev adc device
* @param smp_rate sample rate to set
* @see adc_smp_rate
*/
void adc_set_sample_rate(const adc_dev *dev, adc_smp_rate smp_rate) {
uint32 adc_smpr1_val = 0, adc_smpr2_val = 0;
int i;
for (i = 0; i < 10; i++) {
if (i < 8) {
/* ADC_SMPR1 determines sample time for channels [10,17] */
adc_smpr1_val |= smp_rate << (i * 3);
}
/* ADC_SMPR2 determines sample time for channels [0,9] */
adc_smpr2_val |= smp_rate << (i * 3);
}
dev->regs->SMPR1 = adc_smpr1_val;
dev->regs->SMPR2 = adc_smpr2_val;
}
/**
* @brief Calibrate an ADC peripheral
* @param dev adc device
*/
static void adc_calibrate(const adc_dev *dev) {
__io uint32 *rstcal_bit = (__io uint32*)BITBAND_PERI(&(dev->regs->CR2), 3);
__io uint32 *cal_bit = (__io uint32*)BITBAND_PERI(&(dev->regs->CR2), 2);
*rstcal_bit = 1;
while (*rstcal_bit)
;
*cal_bit = 1;
while (*cal_bit)
;
}
|
