MMC interface with Microcontroller PIC16f877 and serial communication with PC This project is about How to interface MMC with Microcontroller PIC16f877 and serial communication with PC. PIC – MMC (Multi Media Card) Flash Memory Extension It is easy to interface a MMC (MultiMediaCard) with a MicroChip PIC via the SPI (Serial Port Interface). This is a very handy data logging circuit with lots of memory for data storage. I2C RAM’s or EEPROM’s are hardly available at sizes bigger than 256kb, but this solution with a 64MB Flash MMC is not to beat in both cost effectiveness and storage volume! This version utilizes a PIC16F876, but it’s easy to port the schematic and software to other PIC’s. The MMC is connected to the SPI pins of the PIC via simple resistor voltage dividers to transform the +5V high levels to about 3.3V used by the MMC. The supply voltage for <a href="http://wk.putianb2b.com/"><strong>网络兼职招聘 </strong></a> the MMC (2.7V – 3.6V) comes from a LD1086V33 voltage regulator (3.3V) or equivalent. It is possible to run the PIC at 3.3V, but then the AD converters are not as stable as at 5V. The data-out pin from the MMC goes directly to the PIC, because 3.3V is high for the PIC anyway. circuit diagram of the MMC interface with Microcontroller PIC16f877 and serial communication with PC is as below: code of the project is as below:- /* PIC MMC Interface Test
http://www.captain.at/electronics/ Writes ASCII characters to the MMC, reads them back and sends the characters Furthermore the PIC returns any character sent to it via the interrupt service routine. Use “ser” for testing: # ./ser baud=9600 baud=9600 written:ABC readport=ABC # Compile with CC5x:
http://www.bknd.com/cc5x/ c:picccc5x mmc.c -Ic:picc -ammc.ASM -u CC5x runs nicely on Linux with “dosemu”
http://www.dosemu.org/ Credit: SPI functions made by Michael Dworkin
http://home.wtal.de/Mischka/MMC/ */ #include #include “int16CXX.H” // interrupt stuff #define CP_off |= 0x3F30 #define LVP |= 128 #pragma config CP_off,PWRTE=on,WDTE=off,FOSC=HS,BODEN=on,LVP #pragma bit CS @ PORTC.2 // output pin for chip select (MMC) #pragma rambank <a href="http://wk.putianb2b.com/"><strong>成都兼职 </strong></a> 0 char sector1[64]; int currentrambank; int counter; #pragma rambank 1 char sector2[64]; #pragma rambank 2 char sector3[64]; #pragma rambank 3 char sector4[64]; #pragma origin 4 // force interrupt service routine at address 4 interrupt myInterrupt(void) // ISR { int_save_registers char rec; if (RCIF) // USART interrupt ? { while(!TXIF) { // wait for serial register to be sent, if there is still something in there nop(); } rec = RCREG; // Get the received character TXREG = rec; // write to serial register -> start transmission RCIF = 0; // clear USART int flag } int_restore_registers } void InitUSART() { PORTA = 0; PORTB = 0; PORTC = 0; BRGH = 1; // high speed serial mode SPBRG = 25; // Set 9600 baud for 4 MHz oscillator SYNC = 0; // Clear SYNC bit -> Set ASYNC Mode SPEN = 1; // Set serial port enable TX9 = 0; // 8-bit transmissions TXEN = 1; // Enable transmission RCIE = 1; // Rx interrupts are desired RX9 = 0; // 8-bit receptions CREN = 1; // Enable reception } void initint() // init interrupts { GIE = 1; // Set Global Interrupt Enable PEIE = 1; // Set Peripheral Interrupt <a href="http://wk.putianb2b.com/"><strong>国外网赚 </strong></a> Enable } void fillram() // fill RAM (sector1..4) with ASCII characters { int i; int x; for (i=0;i<=63;i++) { x = i + 48; sector1[i] = x; sector2[i] = x; sector3[i] = x; sector4[i] = x; } } char SPI(char d) // send character over SPI { SSPBUF = d; // send character while (!BF); // wait until sent return SSPBUF; // and return the received character } char Command(char befF,uns16 AdrH,uns16 AdrL,char befH ) { // sends a command to the MMC char a; SPI(0xFF); SPI(befF); SPI(AdrH.high8); SPI(AdrH.low8); SPI(AdrL.high8); SPI(AdrL.low8); SPI(befH); SPI(0xFF); return SPI(0xFF); // return the last received character } bit MMC_Init() // init SPI { SMP = 0; // input is valid in the middle of clock CKE = 0; // rising edge is data capture CKP = 1; // high value is passive state SSPM1 = 1; // speed f/64(312kHz), Master SSPEN = 1; // enable SPI CS = 1; // disable MMC char i; // start MMC in SPI mode for(i=0; i 0) // test if end of string is reached { str++; // set pointer to next char if (ps== 0) break; // test if end of string is reached while(!TXIF); // test if TXREG empty TXREG = ps ; // send character ps = *str; // content of pointer into ps } serialterminate(); } bit writeramtommc() // write RAM (sector1..4) to MMC { // 512 byte-write-mode if (Command(0×58,0,512,0xFF) !=0) { SerString(“MMC: write error 1 “); return 1; } SPI(0xFF); SPI(0xFF); SPI(0xFE); uns16 i; // write ram sectors to MMC for (i=0;i<=63;i++) { SPI(sector1[i]); } for (i=0;i<=63;i++) { SPI(sector2[i]); } for (i=0;i<=63;i++) { SPI(sector3[i]); } for (i=0;i<=63;i++) { SPI(sector4[i]); } for (i=0;i<256;i++) { // fill rest with 'C' SPI('C'); } SPI(255); // at the end, send 2 dummy bytes SPI(255); i = SPI(0xFF); i &= 0b.0001.1111; if (i != 0b.0000.0101) { SerString("MMC: write error 2 "); return 1; } while(SPI(0xFF) != 0xFF); // wait until MMC is not busy anymore return 0; } bit sendmmc() // send 512 bytes from the MMC via the serial port { uns16 i; // 512 byte-read-mode if (Command(0×51,0,512,0xFF) !=0) { SerString("MMC: read error 1 "); return 1; } while(SPI(0xFF) != 0xFE); // wait for 0xFE – start of any transmission for(i=0; i TX, RB1>RX SerString(“PIC online “); // start message // SerString(0×00); // start message // init MMC and send message <a href="http://rooyee.org/view.php?id=35432"><strong>Russian Market Of Leather Goods (leather ... - GANM timberland uk</strong></a> if ok if (MMC_Init()) SerString(“MMC online “); fillram(); // fill the RAM with ASCII characters writeramtommc(); // write RAM to MMC sendmmc(); // send 512 bytes of the MMC via serial port while(1) { nop(); nop(); } }
MMC interface with Microcontroller PIC16f877 and serial ...
Linear Mode
