Motorola Semiconductor Engineering Bulletin EB422 Enhanced
Motorola Semiconductor Engineering Bulletin EB422 Enhanced
Motorola Semiconductor Engineering Bulletin EB422 Enhanced
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Freescale <strong>Semiconductor</strong>, Inc...<br />
<strong>Engineering</strong> <strong>Bulletin</strong><br />
Freescale <strong>Semiconductor</strong>, Inc.<br />
Listing 7. MC68HC11ED0 Bootloader ROM Listing<br />
0001 *Bootloader Firmware for MC68HC11ED0<br />
0002<br />
0003 ********************************************************<br />
0004 * November 11 1991<br />
0005 ********************************************************<br />
0006<br />
0007 * Equates for use with index offset = 0<br />
0008<br />
0009 0008 PORTD EQU $08<br />
0010 0009 DDRD EQU $09<br />
0011 0028 SPCR EQU $28<br />
0012 002b BAUD EQU $2B<br />
0013 002c SCCR1 EQU $2C<br />
0014 002d SCCR2 EQU $2D<br />
0015 002e SCSR EQU $2E<br />
0016 002f SCDAT EQU $2F<br />
0017 003b PPROG EQU $3B<br />
0018 003f CONFIG EQU $3F<br />
0019<br />
0020 ********************************************************<br />
0021 * This bootstrap program allows the user to<br />
0022 * download a program of exactly 256 bytes.<br />
0023 * The program must start at $0100.<br />
0024 * Each byte of the program is received by the<br />
0025 * SCI, starting with the $0100 byte and working<br />
0026 * up to the $01FF.<br />
0027 *<br />
0028 * This bootloader is based on the bootloader for the<br />
0029 * MC68HC11A8. Modifications are to place the registers<br />
0030 * at $00XX and destination to $0100.<br />
0031 ********************************************************<br />
0032 bf80 ORG $BF80<br />
0033 bf80 BEGIN EQU *<br />
0034<br />
0035 * Init.stack<br />
0036 bf80 8e 00 ff LDS #$00FF<br />
0037 * Put PORTD in wired-or mode<br />
0038 bf83 14 28 20 BSET SPCR $20<br />
0039 * Init SCI, restart the divider chain, enable tx & rx<br />
0040 bf86 cc a2 0c LDD #$A20C<br />
0041 bf89 97 2d STAA BAUD<br />
0042 bf8b d7 2d STAB SCCR2<br />
0043 * Send break as soon as start bit is detected<br />
0044 bf8d 14 2d 01 BSET SCCR2 $01<br />
0045 * Clear break as soon as start bit is detected<br />
0046 bf90 12 08 01 fc BRSET PORTD $01 *<br />
0047 bf94 15 2d 01 BCLR SSCR2 $01 * Clear break<br />
0048 * Wait for first character (users send $ff)<br />
0049 bf97 13 2e 20 fc BRCLR SCSR $20 * Wait for RDRF<br />
0050 bf9b 96 2f LDAA SCDAT Read data<br />
0051 *** No jump to EEPROM or RAM here !!<br />
0052 * If data = $FF, then /16 is correct baud<br />
0053 bf9d 81 ff CMPA #$FF<br />
0054 bf9f 27 03 BEQ BAUDOK<br />
0055 * else change to /104 (/13 & /8) 1200 @ 2 MHz<br />
0056 bfa1 14 2b 33 BSET BAUD $33<br />
0057 * Then download 256 byte program<br />
0058 bfa4 BAUDOK EQU *<br />
0059 bfa4 ce 01 00 LDX #$100 Init pointer<br />
0060 * Read in program and put in RAM<br />
0061 bfa7 BK2 EQU *<br />
<strong>EB422</strong><br />
14 MOTOROLA<br />
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