PIC32MX: RS232 - Revision history

Andrew Long: /* PIC to PC */

2010-01-14T05:24:14Z

PIC to PC

Andrew Long: /* Interrupt Example Code */

2010-01-05T22:36:35Z

Interrupt Example Code

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Andrew Long: /* Basic Sample Code */

2010-01-05T22:31:43Z

Basic Sample Code

Andrew Long: /* Basic Sample Code */

2010-01-05T22:26:34Z

Basic Sample Code

Andrew Long: /* Basic Sample Code */

2010-01-05T22:25:43Z

Basic Sample Code

Andrew Long: /* Basic Sample Code */

2010-01-05T22:25:28Z

Basic Sample Code

Andrew Long: /* Basic Sample Code */

2010-01-05T22:25:13Z

Basic Sample Code

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Andrew Long at 20:45, 27 August 2009

2009-08-27T20:45:40Z

Andrew Long at 20:44, 27 August 2009

2009-08-27T20:44:52Z

Andrew Long: /* Basic Sample Code */

2009-08-26T21:27:47Z

Basic Sample Code

@@ Line 13: / Line 13: @@
 =PIC to PC=
 [[Image:usb-rs232-cable.jpg|right]]
-To communicate PIC to PC, you need to have a COMM port or a USB to RS232 converter. You can read about the TTL-232R cable (USB to RS232 converter) [[PIC RS232#FTDIChip TTL-232R USB to RS232 Cable |here]].
+To communicate PIC to PC, you need to have a COMM port or a USB to RS232 converter. You can read about the TTL-232R cable (USB to RS232 converter) [[PIC RS232#FTDIChip TTL-232R USB to RS232 Cable |here]]. Download the [http://www.ftdichip.com/Drivers/CDM/CDM%202.02.04.exe driver software].
 The TTL-232R cable has six wires, color coded and in this sequence on the SIP connector:
@@ Line 31: / Line 31: @@
 <br clear=all>
 The code demonstrated below can also be used for [[XBee radio communication between PICs|Xbee communication]]. Simply put an xbee connected to the PIC with the RX, TX, GND and 5V and then connect the other xbee to the TTL-232R cable.
 =Basic Sample Code=

@@ Line 34: / Line 34: @@
 =Basic Sample Code=
-This code details how to echo typing in a terminal such as Hyper Terminal. The PIC reads the pressed key from the PC and then transmits the key back to the PC via the TTL-232R cable. The key will be displayed on the terminal. If the key 'c' is pressed, LED1 will turn on (turns off LED2 if on). If a different key is pressed, LED2 will turn on (turns off LED1 if on). Notice how this code has to wait until a character is read. The next example uses interrupts to detect when a key is pressed.
+This code details how to echo typing in a terminal such as Hyper Terminal. The PIC reads the pressed key from the PC and then transmits the key back to the PC via the TTL-232R cable. The key will be displayed on the terminal. If the key 'c' is pressed, LED1 will turn on (turns off LED2 if on). If a different key is pressed, LED2 will turn on (turns off LED1 if on). Notice how this code has to wait until a character is read. The next example uses interrupts to detect when a key is pressed. This code shows many different constants for the 2 configuration variables (config1 and config2). Most of these are default constants. To see other options inspect uart.h in C:\Program Files\Microchip\MPLAB C32\pic32mx\include\peripheral.
  /*********************************************************************

@@ Line 34: / Line 34: @@
 =Basic Sample Code=
-This code details how to echo typing in a terminal such as Hyper Terminal. The PIC reads the pressed key from the PC and then transmits the key back to the PC via the TTL-232R cable. The key will be displayed on the terminal. If the key 'c' is pressed, LED1 will turn on (turns off LED2 if on). If a different key is pressed, LED2 will turn on (turns off LED1 if on).
+This code details how to echo typing in a terminal such as Hyper Terminal. The PIC reads the pressed key from the PC and then transmits the key back to the PC via the TTL-232R cable. The key will be displayed on the terminal. If the key 'c' is pressed, LED1 will turn on (turns off LED2 if on). If a different key is pressed, LED2 will turn on (turns off LED1 if on). Notice how this code has to wait until a character is read. The next example uses interrupts to detect when a key is pressed.
  /*********************************************************************

@@ Line 72: / Line 72: @@
  		// CTS and RTS pins are disabled
  		// UxRX idle state is '1'
-		// 16x baud clock - normal speed
+ 		// 16x baud clock - normal speed
  	#define config1 	UART_EN | UART_IDLE_CON | UART_RX_TX | UART_DIS_WAKE | UART_DIS_LOOPBACK | UART_DIS_ABAUD | UART_NO_PAR_8BIT | UART_1STOPBIT | UART_IRDA_DIS | UART_DIS_BCLK_CTS_RTS| UART_NORMAL_RX | UART_BRGH_SIXTEEN

@@ Line 73: / Line 73: @@
  		// UxRX idle state is '1'
 		// 16x baud clock - normal speed
-	#define config1 	UART_EN | UART_IDLE_CON | UART_RX_TX | UART_DIS_WAKE | UART_DIS_LOOPBACK | UART_DIS_ABAUD | UART_NO_PAR_8BIT | UART_1STOPBIT | UART_IRDA_DIS | UART_DIS_BCLK_CTS_RTS| UART_NORMAL_RX | UART_BRGH_SIXTEEN
+ 	#define config1 	UART_EN | UART_IDLE_CON | UART_RX_TX | UART_DIS_WAKE | UART_DIS_LOOPBACK | UART_DIS_ABAUD | UART_NO_PAR_8BIT | UART_1STOPBIT | UART_IRDA_DIS | UART_DIS_BCLK_CTS_RTS| UART_NORMAL_RX | UART_BRGH_SIXTEEN
  	// define setup Configuration 2 for OpenUARTx

@@ Line 8: / Line 8: @@
 *UxRX  - PIC receive
 *UxTX  - PIC transmit
+This code has been tested with the [[XBee radio communication between PICs|Xbees]] also.
 __TOC__
 =PIC to PC=

@@ Line 8: / Line 8: @@
 *UxRX  - PIC receive
 *UxTX  - PIC transmit
+__TOC__
 =PIC to PC=
 [[Image:usb-rs232-cable.jpg|right]]
@@ Line 28: / Line 28: @@
 *PC Receive -- PIC Transmit
 <br clear=all>
+The code demonstrated below can also be used for [[XBee radio communication between PICs|Xbee communication]]. Simply put an xbee connected to the PIC with the RX, TX, GND and 5V and then connect the other xbee to the TTL-232R cable.
 =Basic Sample Code=
 This code details how to echo typing in a terminal such as Hyper Terminal. The PIC reads the pressed key from the PC and then transmits the key back to the PC via the TTL-232R cable. The key will be displayed on the terminal. If the key 'c' is pressed, LED1 will turn on (turns off LED2 if on). If a different key is pressed, LED2 will turn on (turns off LED1 if on).
@@ Line 118: / Line 121: @@
       return 0;
    }
+Compile and Program this Hex file to the PIC.
+Open Hyperterminal with the following information:
+*Bits per second: 9600
+*Data bits: 8
+*Parity: None
+*Stop bits: 1
+*Flow Control: Hardware
+If you press reset on the PIC32 board, you should see the start up message.
+=Interrupt Example Code=
+This code details how to echo typing in a terminal such as Hyper Terminal. This code uses an interrupt to communicate via RS232. The above code waits in a while loop until the PIC receives a character. The code below does not have to sit and wait. An interrupt is called when it receives a character to trigger RS232 communication. The PIC reads the pressed key from the PC and then transmits the key back to the PC via the TTL-232R cable. The key will be displayed on the terminal. If the key 'c' is pressed, LED2 will turn on (turns off LED3 if on). If a different key is pressed, LED3 will turn on (turns off LED2 if on). LED1 toggles when there is RS232 activity.
+Include the standard header files
+   #include "Compiler.h"
+   #include <plib.h>
+   #include "HardwareProfile.h"
+Define the system frequency and the desired baudrate.
+   #define SYS_FREQ 				(80000000L)
+   #define DESIRED_BAUDRATE    	(9600)      // The desired BaudRate
+Define a global variable for the data
+   volatile unsigned char data;
+Start Main function
+   int main(void)
+   {
+Define local variables for the peripheral bus clock and data.
+   int	pbClk;
+Configure the system - this function returns the peripheral bus clock
+   pbClk = SYSTEMConfigPerformance(SYS_FREQ);
+Initialize LEDs
+   mInitAllLEDs();
+Setup Configuration 1 for OpenUARTx (most of these are default and not needed). Other constants can be found in uart.h in the peripheral include of C32.
+*Module Enable
+*Work in IDLE mode
+*Communication through usual pins
+*Disable wake-up
+*Loop back disabled
+*Input to Capture module from ICx pin
+*No parity 8 bit
+*1 stop bit
+*IRDA encoder and decoder disabled
+*CTS and RTS pins are disabled
+*UxRX idle state is '1'
+*16x baud clock - normal speed
+   #define config1 	UART_EN | UART_IDLE_CON | UART_RX_TX | UART_DIS_WAKE | UART_DIS_LOOPBACK | UART_DIS_ABAUD | UART_NO_PAR_8BIT | UART_1STOPBIT | UART_IRDA_DIS | UART_DIS_BCLK_CTS_RTS| UART_NORMAL_RX | UART_BRGH_SIXTEEN
+Setup Configuration 2 for OpenUARTx
+*IrDA encoded UxTX idle state is '0'
+*Enable UxRX pin
+*Enable UxTX pin
+*Interrupt on transfer of every character to TSR
+*Interrupt on every char received
+*Disable 9-bit address detect
+*Rx Buffer Over run status bit clear
+   #define config2		UART_TX_PIN_LOW | UART_RX_ENABLE | UART_TX_ENABLE | UART_INT_TX | UART_INT_RX_CHAR | UART_ADR_DETECT_DIS | UART_RX_OVERRUN_CLEAR
+Open UART2 with config1 and config2. The third input is the value to get the generated BAUD value (not exact to the desired).
+   OpenUART2( config1, config2, pbClk/16/DESIRED_BAUDRATE-1);	// calculate actual BAUD generate value.
+Configure UART2 RX Interrupt with priority 2
+   ConfigIntUART2(UART_INT_PR2 | UART_RX_INT_EN);
+Must enable glocal interrupts - in this case, we are using multi-vector mode
+   INTEnableSystemMultiVectoredInt();
+Display start up information. The function putsUARTx is used to display strings.
+   putsUART2("*** UART Interrupt-driven Application Example ***\r\n");
+   putsUART2("*** Type some characters and observe echo and LED1 toggle  ***\r\n");
+Enter while loop
+      while(1) //let interrupt handle the UART
+      {
+      };
+      return 0;
+   } // end main function
+UART 2 interrupt handler with priority level set at 2
+   void __ISR(_UART2_VECTOR, ipl2) IntUart2Handler(void)
+   {
+        //Is this an RX interrupt?
+        if(mU2RXGetIntFlag())
+        {
+            // Clear the RX interrupt Flag
+            mU2RXClearIntFlag();
+            //Read the data
+            data = (char) ReadUART2();
+            // Echo what we just received.
+            putcUART2(data);
+            // Toggle LED to indicate UART activity
+            mLED_1_Toggle();
+            if(data == 'c')
+            {
+               mLED_2_On();
+               mLED_3_Off();
+            }
+            else
+            {
+               mLED_3_On();
+               mLED_2_Off();
+            }
+         }
+        // We don't care about TX interrupt
+        if ( mU2TXGetIntFlag() )
+        {
+            mU2TXClearIntFlag();
+        }
+   } // end ISR
 Compile and Program this Hex file to the PIC.