{"id":277,"date":"2013-03-14T14:25:40","date_gmt":"2013-03-14T21:25:40","guid":{"rendered":"https:\/\/www.uniteng.com\/?p=277"},"modified":"2021-01-05T14:45:46","modified_gmt":"2021-01-05T06:45:46","slug":"raspberry-pi-with-relay-io-board","status":"publish","type":"post","link":"https:\/\/www.uniteng.com\/index.php\/2013\/03\/14\/raspberry-pi-with-relay-io-board\/","title":{"rendered":"Raspberry Pi with Relay I\/O Board"},"content":{"rendered":"

\n\tRelay I\/O Board is widely used in applications of smart home project. In this article, I will detail how to control the Relay I\/O board using Raspberry Pi with Raspberry Pi Universal Expansion Board<\/a> via internet. The codes and schematic diagrams used in this article was listed at the end of this article.\n<\/p>\n

\n\tPart I: Hardware<\/strong>\n<\/p>\n

\n\t1. Pin Mapping<\/strong>\n<\/p>\n

\n\tThe CPLD on the Raspberry Pi Universal Expansion Board can be used to map pins between modules. For this project, we want to map pins as following diagram Fig.1. \"ConnectionMap_Temp\"<\/a>\n<\/p>\n

\n\tFig. 1 Pin Mapping\n<\/div>\n

\n\tThis part is pretty easy since we only need to map the UART1 of the STM32 to the Raspberry Pi and PC10, PC11 of the STM32 to the Relay I\/O board using the CPLD. The following Verilog code can implement the idea:\n<\/p>\n

\r\nmodule RS232(RXD_in,TXD_in,RXD_out,TXD_out,\r\nK1_in,K1_out,K2_in,K2_out);\r\n\r\ninput   RXD_in, TXD_in,K1_in,K2_in;\r\noutput  RXD_out,TXD_out,K1_out,K2_out;\r\n\r\nassign RXD_out = RXD_in;\r\nassign TXD_out = TXD_in;\r\n\r\n\/\/assign pins for relays K1 and K2\r\nassign K1_out = K1_in;\r\nassign K2_out = K2_in;\r\n\r\nendmodule\r\n<\/pre>\n
\n\tNavigate to Quartus -> Assignments -> Pin Planner. The IO need to be configured as following picture.\n<\/p>\n
\n\t\"UEB_Relay_Pins\"<\/a>\n<\/p>\n
\n\tWe can flash the design into the CPLD right now.\n<\/p>\n
\n\t2. STM32 Configuration<\/strong>\n<\/p>\n
\n\tCreating a new .c source code file RelayIOBoard.c as the driver of the Relay I\/O board:\n<\/p>\n
\r\n\/*Driver for Relay IO board*\/\r\n#include < stm32f10x.h>\r\n#include < stdio.h>\r\n\r\n#define on  1\r\n#define off 0\r\n\r\nint k1_state;\r\nint k2_state;\r\n\r\nvoid Relay(int relay_num, int on_off){\r\n  switch( relay_num ) \r\n  {\r\n    case 1:\r\n\t\t\t\/\/For K1 which is controlled by the PC10\r\n        if(on_off == on)\r\n\t\t\t\t{\r\n         GPIO_SetBits(GPIOC, GPIO_Pin_10);\r\n\t\t\t\t k1_state = on;\r\n        }\r\n        if(on_off == off)\r\n\t\t\t\t{\r\n         GPIO_ResetBits(GPIOC, GPIO_Pin_10);\r\n\t\t\t\t k1_state = off;\r\n        }\t\t\t\t\r\n        break;\r\n    case 2 :\r\n\t\t\t\/\/For K2 which is controlled by the PC11\r\n        if(on_off == on)\r\n\t\t\t\t{\r\n         GPIO_SetBits(GPIOC, GPIO_Pin_11);\r\n\t\t\t\t k2_state = on;\r\n        }\r\n        if(on_off == off)\r\n\t\t\t\t{\r\n         GPIO_ResetBits(GPIOC, GPIO_Pin_11);\r\n\t\t\t\t k2_state = off;\r\n        }\t\t\r\n        break;\r\n  }\r\n}\r\n\r\nvoid Get_Relay_States(void){\r\n   if(k1_state == on){\r\n      printf("k1on\\r\\n");\r\n   }\r\n\t else{\r\n      printf("k1off\\r\\n");\r\n   }\r\n   if(k2_state == on){\r\n      printf("k2on\\r\\n");\r\n   }\r\n\t else{\r\n      printf("k2off\\r\\n");\r\n   }\r\n}\r\n\r\nvoid Relay_init(void )\r\n{\r\n  Relay(1,off);\r\n\tRelay(2,off);\r\n\tk1_state =off;\r\n\tk2_state =off;\r\n}\r\n\r\n<\/pre>\n
\n\tWe need to add following commands to the Shell() in CommandShell.c:\n<\/p>\n
\r\n\t \/\/Command K1 on\r\n\t if(IsStringMatch(Command,"k1on",Counter)){\r\n\t\t  Relay(1, 1);\r\n\t\t printf("k1on\\r\\n");\r\n\t   }\r\n\t \/\/Command K1 off\r\n\t if(IsStringMatch(Command,"k1off",Counter)){\r\n\t\t  Relay(1, 0);\r\n\t\t printf("k1off\\r\\n");\r\n\t   }\r\n\t \/\/Command K2 on\r\n\t if(IsStringMatch(Command,"k2on",Counter)){\r\n\t\t  Relay(2, 1);\r\n\t\t printf("k2on\\r\\n");\r\n\t   }\r\n\t \/\/Command K2 off\r\n\t if(IsStringMatch(Command,"k2off",Counter)){\r\n\t\t  Relay(2, 0);\r\n\t\t printf("k2off\\r\\n");\r\n\t   }\r\n\t \/\/Command krs, get relay states\r\n\t if(IsStringMatch(Command,"krs",Counter)){\r\n\t\t  Get_Relay_States();\r\n\t   }\r\n<\/pre>\n
\n\tFor convenience, the Firmware STM32_Relay_1.0.hex<\/a> needs to be flashed into the MCU. The Firmware will host a Command Shell on UART1. It also includes the driver of the Relay I\/O board.\n<\/p>\n
\n\t3. Testing<\/strong>\n<\/p>\n
\n\tConnecting Relay I\/O Board to the Pmod1 socket<\/a> on the Raspberry Pi Universal Expansion Board. A cooling fan may be controlled by the relay as following figure. \"UEB_Relay_Testing\"<\/a>\n<\/p>\n
\n\tEntering following command in the Linux shell of the Raspberry Pi:\n<\/p>\n
\r\nminicom -b 9600 -o -D \/dev\/ttyAMA0\r\n<\/pre>\n
\n\tTry k1on, k1off, k2on and k2off commands to control the relays.\n<\/p>\n
\n\tPart II: Software<\/strong>\n<\/p>\n