1 /*
2 * @brief Digital to Analog converter example.
3 *
4 * @note
5 * Copyright(C) NXP Semiconductors, 2014
6 * All rights reserved.
7 *
8 * @par
9 * Software that is described herein is for illustrative purposes only
10 * which provides customers with programming information regarding the
11 * LPC products. This software is supplied "AS IS" without any warranties of
12 * any kind, and NXP Semiconductors and its licensor disclaim any and
13 * all warranties, express or implied, including all implied warranties of
14 * merchantability, fitness for a particular purpose and non-infringement of
15 * intellectual property rights. NXP Semiconductors assumes no responsibility
16 * or liability for the use of the software, conveys no license or rights under any
17 * patent, copyright, mask work right, or any other intellectual property rights in
18 * or to any products. NXP Semiconductors reserves the right to make changes
19 * in the software without notification. NXP Semiconductors also makes no
20 * representation or warranty that such application will be suitable for the
21 * specified use without further testing or modification.
22 *
23 * @par
24 * Permission to use, copy, modify, and distribute this software and its
25 * documentation is hereby granted, under NXP Semiconductors' and its
26 * licensor's relevant copyrights in the software, without fee, provided that it
27 * is used in conjunction with NXP Semiconductors microcontrollers. This
28 * copyright, permission, and disclaimer notice must appear in all copies of
29 * this code.
30 */
31
32 #include "board.h"
33
34 /*****************************************************************************
35 * Private types/enumerations/variables
36 ****************************************************************************/
37
38 /* DAC internal timer reload value to generate interrupts at 2KHz or 0.5ms*/
39 #define DAC_TIM_RELOAD ((uint32_t) 0x8C9F)
40 /* Increments for DAC input at every interrupt to generate a saw tooth wave of 100Hz*/
41 #define DAC_IN_UPDATE ((uint32_t) 215)
42
43 static volatile uint32_t dac_input;
44
45 /*****************************************************************************
46 * Public types/enumerations/variables
47 ****************************************************************************/
48
49 /*****************************************************************************
50 * Private functions
51 ****************************************************************************/
52
53 /* DAC OUT Pin mux function - note that SystemInit() may already setup your
54 pin muxing at system startup */
Init_DAC_PinMux(void)55 static void Init_DAC_PinMux(void)
56 {
57 #if defined(BOARD_NXP_LPCXPRESSO_1549)
58 /* Disables pullups/pulldowns and disable digital mode */
59 Chip_IOCON_PinMuxSet(LPC_IOCON, 0, 12, (IOCON_MODE_INACT | IOCON_ADMODE_EN));
60
61 /* Assign DAC_OUT to P0.12 via SWM (fixed pin) */
62 Chip_SWM_EnableFixedPin(SWM_FIXED_DAC_OUT);
63 #else
64 /* Configure your own ACMP pin muxing here if needed */
65 #warning "No DAC Out pin muxing defined"
66 #endif
67 }
68
69 /*****************************************************************************
70 * Public functions
71 ****************************************************************************/
72
73 /**
74 * @brief DAC interrupt handler sub-routine
75 * @return Nothing
76 */
DAC_IRQHandler(void)77 void DAC_IRQHandler(void)
78 {
79 if (Chip_DAC_GetIntStatus(LPC_DAC)) {
80 /* Update DAC Input value*/
81 dac_input += DAC_IN_UPDATE;
82 /* Boundary check for max DAC input*/
83 if (dac_input > 4095) {
84 /* Cycle DAC values */
85 dac_input = 0;
86 }
87 /* Updating DAC Value register will clear interrupt */
88 Chip_DAC_UpdateValue(LPC_DAC, dac_input);
89 }
90 }
91
92 /**
93 * @brief Main program body
94 * @return Does not return
95 */
main(void)96 int main(void)
97 {
98 /* initialize the board */
99 SystemCoreClockUpdate();
100 Board_Init();
101
102 /* initialize the DAC */
103 Chip_DAC_Init(LPC_DAC);
104 /* Setup board specific DAC pin muxing */
105 Init_DAC_PinMux();
106 /* Initialize DAC input to 0 */
107 dac_input = 0;
108 /* Set up DAC internal timer to trigger interrupts every 0.5ms/2KHz */
109 Chip_DAC_SetReqInterval(LPC_DAC, 2000);
110 Chip_DAC_EnableIntTimer(LPC_DAC);
111 /* Disable double buffering */
112 Chip_DAC_EnableDoubleBuffer(LPC_DAC);
113 /* Set trigger source as Internal Timer */
114 Chip_DAC_SetTrgSrcInternal(LPC_DAC);
115 /* Start DAC with zero voltage */
116 Chip_DAC_UpdateValue(LPC_DAC, dac_input);
117 /* Enable the Interrupt for DAC */
118 NVIC_EnableIRQ(DAC_IRQ);
119
120 while (1) {
121 /* Enter low power mode until DAC interrupt */
122 __WFI();
123 }
124
125 return 0;
126 }
127