PIC18F4550 Firmware

This page will cover the creation of the firmware for the REPING program

REPING: A Linux server program constructs a packet of data and sends it to the PIC18F4550 microcontroller using USB communications. The microcontroller reverse the order of the bytes in the packet and send the new packet back to the server. I call this program "reping".

USB API and Sample Code

• \Microchip Solutions\Microchip
  This directory contains the actual Framework API code.
• \Microchip Solutions\USB Device - MCHPUSB - Generic Driver Demo\Generic Driver Demo - Firmware
  This directory contains example firmware code.

Create a new directory called REPING for the new project. Copy the directory \Microchip Solutions\Microchip into the REPING project directory.

Navigate to the \Microchip Solutions\USB Device - MCHPUSB - Generic Driver Demo\Generic Driver Demo - Firmware" directory. Copy the following files into the REPING directory.

• HardwareProfile.h
• main.c
• usb_config.h
• user.h
• user.c
• usb_descriptors.c
• rm18f4550.lkr

New Project

Adding Files

• Right click on the Sources icon and select Add Files.... Navigate to the REPING directory and add all the "*.c" files we copied earlier.
• Right click on the Header Files icon and select Add Files.... Add all of the "*.h" files we copied earlier.
• Right click on the Linker icon and select Add Files.... Add the rm18f4550.lkr file we copied earlier.
  WARNING: If you don't use the linker file from the demo directory, the program will not function!!!
• Right click on the Sources icon and select Add Files.... Navigate to the directory \Microchip\USB and add the file usb_device.c

Customizing

I replaced the contents of my Hardware.h file with the following:

Hardware.h
#ifndef __MY_HARDWARE_H_ #define __MY_HARDWARE_H_ #define self_power 0 #define USB_BUS_SENSE 1 #include <p18f4550.h> #define PTR_BASE WORD #define __attribute__(a) #define ROM rom #define strcpypgm2ram(a, b) strcpypgm2ram(a,(far rom char*)b) /* Valid Options: 8, 16, 32, or 64 bytes. */ #define EP0_BUFF_SIZE 8 #define USB_MAX_EP_NUMBER 1 #include "GenericTypeDefs.h" #include "USB/usb_device.h" #include "USB/usb.h" #include "USB/usb_function_generic.h" #define U1ADDR UADDR #define U1IE UIE #define U1IR UIR #define U1EIR UEIR #define U1EIE UEIE #define U1CON UCON #define U1EP0 UEP0 #define U1CONbits UCONbits #define U1EP1 UEP1 #define U1CNFG1 UCFG #define U1STAT USTAT #define U1EP0bits UEP0bits #endif

The main.c program has a configuration section marked by /** CONFIGURATION **/. This section attempts to determin the configuration for the board. This configuration section can be replaced with the following:

main.c: /** Configuration **/
/* You will need to configure these for your oscillator */ #pragma config PLLDIV=5 #pragma config CPUDIV=OSC1_PLL2 #pragma config USBDIV=2 #pragma config FOSC=HSPLL_HS #pragma config FCMEN=OFF #pragma config IESO=OFF #pragma config VREGEN=ON #pragma config CCP2MX=ON #pragma config WDT=OFF #pragma config WDTPS=32768 #pragma config PBADEN=OFF #pragma config PWRT=OFF #pragma config MCLRE=ON #pragma config LPT1OSC=OFF #pragma config BOR=ON #pragma config BORV=3 #pragma config STVREN=ON #pragma config LVP=OFF #pragma config ICPRT= OFF #pragma config XINST=OFF #pragma config DEBUG=OFF #pragma config WRTB=ON

The user.c file is heavily modified. Here is the complete user.c file.

user.c
/** INCLUDES *******************************************************/ #include "Compiler.h" #include "GenericTypeDefs.h" #include "HardwareProfile.h" #include "usb_config.h" #include "USB/usb_device.h" #include "USB/usb.h" #include "USB/usb_function_generic.h" #include "user.h" /** V A R I A B L E S ********************************************************/ #pragma udata BYTE counter; #pragma udata USB_VARS DATA_PACKET INPacket; DATA_PACKET OUTPacket; #pragma udata USB_HANDLE USBGenericOutHandle = 0; USB_HANDLE USBGenericInHandle = 0; // Timer0 - 1 second interval setup. // Fosc/4 = 12MHz // Use /256 prescalar, this brings counter freq down to 46,875 Hz // Timer0 should = 65536 - 46875 = 18661 or 0x48E5 #define TIMER0L_VAL 0xE5 #define TIMER0H_VAL 0x48 /** P R I V A T E P R O T O T Y P E S ***************************************/ void setStateBits(int value); void setServiceBits(int value); void Show_USB_State(void); void ServiceRequests(void); /** D E C L A R A T I O N S **************************************************/ #pragma code void UserInit(void) { #if defined(__18CXX) /* Init Timer0 for data logging interval (every 1 second) */ T0CON = 0b10010111; /* Timer0 is already enabled by default */ #elif defined(__C30__) #endif TRISB = 0x00; /* configure all PORTB pins for output */ PORTB = 0x00; /* default LED configuration is off */ }//end UserInit /****************************************************************************** * Function: void ProcessIO(void) * * PreCondition: None * * Input: None * * Output: None * * Side Effects: None * * Overview: This function is a place holder for other user routines. * It is a mixture of both USB and non-USB tasks. * * Note: None *****************************************************************************/ void ProcessIO(void) { Show_USB_State(); // User Application USB tasks if((USBDeviceState < CONFIGURED_STATE)||(USBSuspendControl==1)) return; ServiceRequests(); }//end ProcessIO /****************************************************************************** * Function: void ServiceRequests(void) * * PreCondition: None * * Input: None * * Output: None * * Side Effects: USB traffic can be generated * * Overview: This function takes in the commands from the PC from the * application and executes the commands requested * * Note: None *****************************************************************************/ void ServiceRequests(void) { BYTE i; //Check to see if data has arrived if(!USBHandleBusy(USBGenericOutHandle)) { PORTB = (OUTPacket.length << 2); // shift 2 since we have 6 leds. INPacket.length = OUTPacket.length; for (i=0; i<OUTPacket.length; i++) INPacket.data[i] = OUTPacket.data[OUTPacket.length - i - 1]; if(!USBHandleBusy(USBGenericInHandle)) { USBGenericInHandle = USBGenWrite(USBGEN_EP_NUM,(BYTE*)&INPacket,OUTPacket.length+1); } //Re-arm the OUT endpoint for the next packet USBGenericOutHandle = USBGenRead(USBGEN_EP_NUM,(BYTE*)&OUTPacket,USBGEN_EP_SIZE); }//end if }//end ServiceRequests void setStateBits(int value) { PORTB = value | (0b00011111 & LATB); } void setServiceBits(int value) { // PORTB = value | (0b00011111 & LATB); PORTB = value << 2; // | (0b11100000 & LATB); } void Show_USB_State(void) { static int configured = 1; if(USBSuspendControl == 1) { configured = 0; setStateBits(0b00000000); return; } switch (USBDeviceState) { case POWERED_STATE: configured = 0; setStateBits(0b10000000); break; case DETACHED_STATE: configured = 0; setStateBits(0b01000000); break; case ATTACHED_STATE: configured = 0; setStateBits(0b11000000); break; case DEFAULT_STATE: configured = 0; setStateBits(0b00100000); break; case ADDRESS_STATE: configured = 0; setStateBits(0b10100000); break; case CONFIGURED_STATE: if (configured) break; configured = 1; setStateBits(0b11100000); break; } }

The user.h file defines the DATA_PACKET datatype. Here is the new user.h.

user.h
#ifndef REPING_USER_H #define REPING_USER_H /** I N C L U D E S **********************************************************/ #include "GenericTypeDefs.h" #include "usb_config.h" /** S T R U C T U R E S ******************************************************/ typedef union DATA_PACKET { BYTE _byte[USBGEN_EP_SIZE]; struct { BYTE length; BYTE data[USBGEN_EP_SIZE-1]; }; } DATA_PACKET; /** P U B L I C P R O T O T Y P E S *****************************************/ void UserInit(void); void ProcessIO(void); #endif