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git.gir.st - tmk_keyboard.git/blob - tool/mbed/mbed-sdk/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC408X/TARGET_LPC4088_DM/analogin_api.c
1 /* mbed Microcontroller Library
2 * Copyright (c) 2006-2013 ARM Limited
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
16 #include "mbed_assert.h"
17 #include "analogin_api.h"
20 #include "mbed_error.h"
22 #define ANALOGIN_MEDIAN_FILTER 1
24 #define ADC_10BIT_RANGE 0x3FF
25 #define ADC_12BIT_RANGE 0xFFF
27 static inline int div_round_up(int x
, int y
) {
28 return (x
+ (y
- 1)) / y
;
31 static const PinMap PinMap_ADC
[] = {
32 {P0_25
, ADC0_2
, 0x01},
33 {P0_26
, ADC0_3
, 0x01},
37 #define ADC_RANGE ADC_12BIT_RANGE
39 void analogin_init(analogin_t
*obj
, PinName pin
) {
40 obj
->adc
= (ADCName
)pinmap_peripheral(pin
, PinMap_ADC
);
41 MBED_ASSERT(obj
->adc
!= (ADCName
)NC
);
43 // ensure power is turned on
44 LPC_SC
->PCONP
|= (1 << 12);
46 uint32_t PCLK
= PeripheralClock
;
48 // calculate minimum clock divider
49 // clkdiv = divider - 1
50 uint32_t MAX_ADC_CLK
= 12400000;
51 uint32_t clkdiv
= div_round_up(PCLK
, MAX_ADC_CLK
) - 1;
53 // Set the generic software-controlled ADC settings
54 LPC_ADC
->CR
= (0 << 0) // SEL: 0 = no channels selected
55 | (clkdiv
<< 8) // CLKDIV:
56 | (0 << 16) // BURST: 0 = software control
57 | (1 << 21) // PDN: 1 = operational
58 | (0 << 24) // START: 0 = no start
59 | (0 << 27); // EDGE: not applicable
61 // must enable analog mode (ADMODE = 0)
62 __IO
uint32_t *reg
= (__IO
uint32_t*) (LPC_IOCON_BASE
+ 4 * pin
);
65 pinmap_pinout(pin
, PinMap_ADC
);
68 static inline uint32_t adc_read(analogin_t
*obj
) {
69 // Select the appropriate channel and start conversion
71 LPC_ADC
->CR
|= 1 << (int)obj
->adc
;
72 LPC_ADC
->CR
|= 1 << 24;
74 // Repeatedly get the sample data until DONE bit
78 } while ((data
& ((unsigned int)1 << 31)) == 0);
81 LPC_ADC
->CR
&= ~(1 << 24);
83 return (data
>> 4) & ADC_RANGE
; // 12 bit
86 static inline void order(uint32_t *a
, uint32_t *b
) {
94 static inline uint32_t adc_read_u32(analogin_t
*obj
) {
96 #if ANALOGIN_MEDIAN_FILTER
97 uint32_t v1
= adc_read(obj
);
98 uint32_t v2
= adc_read(obj
);
99 uint32_t v3
= adc_read(obj
);
105 value
= adc_read(obj
);
110 uint16_t analogin_read_u16(analogin_t
*obj
) {
111 uint32_t value
= adc_read_u32(obj
);
113 return (value
<< 4) | ((value
>> 8) & 0x000F); // 12 bit
116 float analogin_read(analogin_t
*obj
) {
117 uint32_t value
= adc_read_u32(obj
);
118 return (float)value
* (1.0f
/ (float)ADC_RANGE
);