1. /********************************************************************
2. ;
3. ;modified LPC1114 sample code
4. ;
5. ; RC5 format:
6. ; | S | F | C | 5 sytem bits | 6 command bits |
7. ; | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 0 | 1 | 1 | 1 | 1 |
8. ;
9. ; -----+ +-+ +-+ +-+ +-+ +-+ +---+ +-+ +---+ +-+ +-+ +-+ +----
10. ; | | | | | | | | | | | | | | | | | | | | | | | |
11. ; +-+ +---+ +-+ +-+ +-+ +-+ +-+ +---+ +-+ +-+ +-+ +-+
12. ;
13. ********************************************************************/
14. #include "LPC11xx.h" /* LPC11xx Peripheral Registers */
16. #define RC5_INPUT_PIN (1<< 0x01)
18. #define MIN_HALF_BIT 640 // 640 us
19. #define HALF_BIT_TIME 889 // 889 us
20. #define MAX_HALF_BIT 1140 // 1140 us
21. #define MIN_FULL_BIT 1340 // 1340 us
22. #define FULL_BIT_TIME 1778 // 1778 us
23. #define MAX_FULL_BIT 2220 // 2220 us
25. unsigned char RC5_System; // Format 1 E/N ts4 s3 s3 s1 s0
26. unsigned char RC5_Command; // Format 00c5 c4 c3 c2 c1 c0
27. unsigned char RC5_flag;
29. static signed int low_time;
30. static signed int high_time;
31. static unsigned char half_bit;
32. static unsigned char sys; // system byte
33. static unsigned char cmd; // Command byte
35. void RC5_Init(void)
36. {
37. //GPIO setup
38. //assign input for IR sensor
39. LPC_GPIO0->DIR &= ~(RC5_INPUT_PIN);
40. LPC_IOCON->PIO0_1 |= (1<<5); //turn on hysteresis
41. LPC_SYSCON->SYSAHBCLKCTRL |= (1<<6);//enable GPIO clock
42. NVIC_EnableIRQ(EINT0_IRQn);
44. //timer16 0 setup
45. LPC_SYSCON->SYSAHBCLKCTRL |= (1<<7);
46. LPC_TMR16B0->PR= 48; // prescaler 48, timer runs at 48 MHz / 48 = 1 MHz
47. LPC_TMR16B0->MR0 = 12000; //load match register 0
48. LPC_TMR16B0->MCR = 3; // Interrupt and Reset on MR0
49. NVIC_EnableIRQ(TIMER_16_0_IRQn);
51. LPC_GPIO0->IS &= ~(0x1<<0x01);//interrupt sense - 0 = edge sensitive
52. LPC_GPIO0->IBE |= 0x1<<0x01; //interrupt both edges - 1 = both edges
53. LPC_GPIO0->IE |= ( 0x1 << 0x01); //interrupt enable
55. LPC_TMR16B0->TCR = 1; //Start timer
56. }
58. static void RC5_Shift_Bit(char val)
59. {
60. if (sys & 0x80)
61. {
62. if (cmd & 0x80) // command full ?
63. {
64. sys = 0; // yes, ERROR
65. cmd = 0;
66. }
67. else
68. cmd = (cmd << 1) | val; // shift command
69. }
70. else
71. sys = (sys << 1) | val; // shift system
72. }
74. /************************************************************************
75. ; RC5_Decode (we only take action at a rising edge)
76. ;
77. ; Half(prev) Bit Low Time High Time Action New Half Bit
78. ; -------------------------------------------------------------------
79. ; 0 0 0 Shift 0 0
80. ; 0 0 1 Shift 1 1
81. ; 0 1 0 -ERROR- *
82. ; 0 1 1 Shift 1,0 0
83. ; 1 0 0 Shift 1 1
84. ; 1 0 1 -ERROR- *
85. ; 1 1 0 Shift 1,0 0
86. ; 1 1 1 -ERROR- *
87. ;
88. ***********************************************************************/
89. static void RC5_Decode(void)
90. {
91. unsigned char action;
93. action = half_bit << 2;
95. // Check High Time
96. if ((high_time > MIN_FULL_BIT) && (high_time < MAX_FULL_BIT))
97. action = action | 1; // high_time = long
98. else if (!((high_time > MIN_HALF_BIT) && (high_time < MAX_HALF_BIT)))
99. {
100. sys = 0; // RC5 ERROR
101. cmd = 0;
102. return;
103. }
105. // Check Low Time
107. if ((low_time > MIN_FULL_BIT) && (low_time < MAX_FULL_BIT))
108. action = action | 2; // low_time = long
109. else if (!((low_time > MIN_HALF_BIT) && (low_time < MAX_HALF_BIT)))
110. {
111. sys = 0; // RC5 ERROR
112. cmd = 0;
113. return;
114. }
116. switch (action)
117. {
118. case 0:RC5_Shift_Bit(0); // short low, short high, shift 0
119. break;
120. case 1:RC5_Shift_Bit(1); // short low, long high, shift 1
121. half_bit = 1; // new half bit is true
122. break;
123. case 2:sys = 0; // long low, short high, ERROR
124. cmd = 0;
125. case 3:RC5_Shift_Bit(1); // long low, long high, shift 1,0
126. RC5_Shift_Bit(0);
127. break;
128. case 4:RC5_Shift_Bit(1); // short low, short high, shift 1
129. break;
130. case 5:sys = 0; // short low, long high, ERROR
131. cmd = 0;
132. break;
133. case 6:RC5_Shift_Bit(1); // long low, short high, shift 1,0
134. RC5_Shift_Bit(0);
135. half_bit = 0; // new half bit is false
136. break;
137. case 7:sys = 0; // long low, long high, ERROR
138. cmd = 0;
139. default: break; // invalid
140. }
141. }
143. void PIOINT0_IRQHandler(void)
144. {
145. uint32_t regVal;
147. LPC_TMR16B0->TCR = 0; //disable timer
149. regVal =LPC_GPIO0->MIS & (0x1<<0x01);//get interrupt status
150. if ( regVal )
151. {
153. if( (LPC_GPIO0->DATA & RC5_INPUT_PIN) == RC5_INPUT_PIN) // check rising or falling edge
154. {
155. if (sys == 0) // First pulse ?
156. {
157. low_time= HALF_BIT_TIME; // assume short low time
158. high_time = HALF_BIT_TIME; // assume short high time
159. half_bit= 1; // assume half bit is true
160. cmd = 0x02; // = 00000010, prepare command byte
161. }
162. else
163. low_time = LPC_TMR16B0->TC; // rising, so capture low time
165. RC5_Decode();
166. }
167. else
168. high_time = LPC_TMR16B0->TC; // falling, so capture high time
170. }
171. LPC_TMR16B0->TCR = 1; //enable timer
172. LPC_TMR16B0->TCR = 2; //reset timer
173. LPC_GPIO0->IC |= ( 0x1 << 0x01);//clear interrupt
174. LPC_TMR16B0->TCR = 1; //enable timer
175. }
177. void TIMER16_0_IRQHandler(void)
178. {
179. if ( LPC_TMR16B0->IR & 0x1 )
180. {
181. //timeout has occured.
182. if (cmd & 0x80) // command full ?
183. {
184. RC5_Command = cmd & 0x7F; // OK ! Save command byte
185. RC5_System = sys; // save system byte
186. RC5_flag = 1; // set event to application
187. }
188. sys = 0;
189. cmd = 0;
190. }
191. LPC_TMR16B0->IR = 1; // clear interrupt flag
192. }