Jon Wilder

Well excuse me. I so wasn't aware of that since I'm new here. Honestly I work with both which is why I figured I'd see what everyone else likes to use.

MCS-51, while being an old uC family, seems to be still in use in lots of MIDI gear even today. I've also noticed PIC uC's rise to popularity in the MIDI field as well (I have done MIDI projects with both). Interestingly enough, I've only seen 1 MIDI device that used a Zilog Z80 (the ADA MP1). So, which is your preference and why?

Migration from an F877 to an F887 is pretty simple. The configuration fuses and the init routine should be all you have to change. Differences between the two PICs - F877/F877A - Writing to the ADCON1 SFR changes the analog/digital I/O modes for the ADC and PORT pins F887 - Has 2 dedicated SFR's for controlling the analog input/digital I/O modes for each ADC/PORT pin (ANSEL and ANSELH). These registers reside in register bank 3 on the PIC Even though the F887 has an on chip oscillator, it is not stable enough for the MIDI bit rate. With the on chip oscillator, there is anywhere from a 1-3% error per bit, which exceeds the allowable tolerance spec in the MIDI specification (translates to a 10-30% error per byte). From experience, I would periodically get framing errors when sending/receiving MIDI data while using the internal oscillator. For best results, use a crystal oscillator. You will have 0% error with a crystal oscillator. The minimum xtal speed to use is 4MHz. You can use a 1MHz but you will have to run the UART in high speed BRG mode (TXSTA,BRGH = 1) and you would load SPBRG with the value of 0x01 in this scenario. Here are some BRG values for 31.25Kbps - If TXSTA,BRGH = 0, then use - 4MHz - SPBRG = 0x01 8MHz - SPBRG = 0x03 12MHz - SPBRG = 0x05 16MHz - SPBRG = 0x07 20MHz - SPBRG = 0x09 If TXSTA,BRGH = 1, then use - 1MHz - SPBRG = 0x01 4MHz - SPBRG = 0x07 8MHz - SPBRG = 0x0F 12MHz - SPBRG = 0x17 16MHz - SPBRG = 0x1F 20MHz - SPBRG = 0x27 Configuration Word - I use this for the F887 - ;************************************************************************************************* ;************************************************************************************************* ;** ** ;** Header Information ** ;** ** ;************************************************************************************************* ;************************************************************************************************* list p=16F887, r=dec, w=-302 include <P16F887.INC> __config _CONFIG1, _LVP_OFF & _FCMEN_OFF & _IESO_OFF & _BOREN_OFF & _PWRTE_ON & _WDT_OFF & _HS_OSC ;Debug Off (default) ;Low Voltage Programming Off ;Fail Safe Clock Monitor Off ;Internal External Switchover Mode off ;Brown Out Reset off ;Data Code Protect off (default) ;Program Code Protect off (default) ;RE3 is MCLRE (default) ;Power Up Timer on ;Watchdog Timer off ;Standard Xtal Oscillator ;If using xtal from 1-4MHz, replace FOSC_HS in the configuration word with FOSC_XT (standard crystal oscillator) You don't have to play with _CONFIG2 unless you plan to use brown out reset or you want to write protect the program ROM space from being written to in code. A basic init routine for a 16F887 running a 16MHz xtal, all ports in output mode and all ADC lines set up for digital I/O - ;************************************************************************************************* ;************************************************************************************************* ;** ** ;** Initialization Routine ** ;** ** ;************************************************************************************************* ;************************************************************************************************* org 0x000 ;reset vector goto START org 0x004 ;interrupt vector ; goto ISR ;uncomment this line if you plan to use interrupts START clrf PORTA ;init port latches clrf PORTB clrf PORTC clrf PORTD clrf PORTE banksel ANSEL ;select RAM bank 3 clrf ANSEL ;AN0 - AN7 digital I/O mode clrf ANSELH ;AN8 - AN13 digital I/O mode banksel TRISA ;select RAM bank 1 clrf TRISA ;PORTA all outputs clrf TRISB ;PORTB all outputs movlw b'11000000' ;RC0-RC5 outputs movwf TRISC ;RC6 UART TX, RC7 UART RX clrf TRISD ;PORTD all outputs clrf TRISE ;PORTE all outputs ;UART init movlw 0x07 ;bit rate = 31.25Kbps for MIDI movwf SPBRG ;w/16MHz crystal movlw b'00100000' ;asynchronous serial, enable UART tx movwf TXSTA banksel 0 ;select RAM bank 0 movlw b'10010000' ;enable serial port movwf RCREG ;enable continuous rx If you're coding in Hitech C and assuming you're using Hitech C v9.83 (the header file definitions seem to change from one Hitech C release to the next...not sure why), the same code would look like such (again using 16MHz xtal and all ports set to output) - /* ********************************************************************************** ********************************************************************************** ** ** ** Header Information ** ** ** ********************************************************************************** ********************************************************************************** */ /* * Hitech C v9.83 - consult your Hitech C p16f887.h file for the correct config word * mnemonics if using an older version of Hitech C */ #include <htc.h> __CONFIG(LVP_OFF & FCMEN_OFF & IESO_OFF & BOREN_OFF & PWRTE_ON & WDTE_OFF & FOSC_HS); /* * Debug Off (default) * Low Voltage Programming Off * Fail Safe Clock Monitor Off * Internal External Switchover Mode off * Brown Out Reset off * Data Code Protect off (default) * Program Code Protect off (default) * RE3 is MCLRE (default) * Power Up Timer on * Watchdog Timer off * Standard Xtal Oscillator * If using xtal from 1-4MHz, replace FOSC_HS in the configuration word with FOSC_XT (standard crystal oscillator) */ /* ********************************************************************************** ********************************************************************************** ** ** ** Interrupt Handler ** ** ** ********************************************************************************** ********************************************************************************** */ void interrupt isr(void) { //place interrupt handler code here (if applicable) } /* ********************************************************************************** ********************************************************************************** ** ** ** Main Code Block ** ** ** ********************************************************************************** ********************************************************************************** */ void main(void) { PORTA = 0x00; //init port latches prior to switching to output mode PORTB = 0x00; PORTC = 0x00; PORTD = 0x00; PORTE = 0x00; ANSEL = 0x00; //AN0 - AN7 digital I/O mode ANSELH = 0x00; //AN8 - AN13 digital I/O mode TRISA = 0x00; //RA0 - RA5 all outputs TRISB = 0x00; //RB0 - RB7 all outputs TRISC = 0b11000000; //RC0 - RC5 outputs, RC6 UART TX, RC7 UART RX TRISD = 0x00; //RD0 - RD7 all outputs TRISE = 0x00; //RE0 - RE2 all outputs //UART initialization SPBRG = 0x07; //31.25Kbps for MIDI w/16MHz xtal TXSTA = 0b00100000; //enable asynchronous mode, enable transmit RCSTA = 0b10010000; //enable serial port, enable continuous rx //main code goes here } Other than that, the rest of your 877A code should remain the same. Hope this helps.