Файл: Microcontroller Programming. Thi Micro Chip PIC (Julio Sanchez, 2007).pdf

;===============================

;first text string procedure ;=============================== storeMS1:

;Procedure to store in PIC RAM buffer the message

;contained in the code area labeled msg1

;ON ENTRY:

;variable bufAdd holds address of text buffer

;in PIC RAM

;w register hold offset into storage area

;msg1 is routine that returns the string characters

;and a zero terminator

;index is local variable that hold offset into

;text table. This variable is also used for

;temporary storage of offset into buffer

;ON EXIT:

;Text message stored in buffer

;

;Store offset into text buffer (passed in the w register)

;in temporary variable

; Initialize index for text string access

;ASSERT: valid string character in w

;store character in text buffer (by FSR)

;Routine for returning message stored in program area

;Message has 10 characters

msg1:

;========================

;blank buffer ;========================

;Procedure to store 20 blank characters in PIC RAM

;buffer starting at address stored in the variable

;bufAdd

blank20:

movwf count1

;============================================================== ; communications procedures ;==============================================================

;Initialize serial port for 2400 baud, 8 bits, no parity,

;1 stop

InitSerial:

;Bits 6 and 7 of Port-C are multiplexed as TX/CK and RX/DT

;for USART operation. These bits must be set to input in the

;TRISC register

;where x is value in the SPBRG register and S is 64 if the high

;baud rate select bit (BRGH) in the TXSTA control register is

;clear, and 16 if the BRGH bit is set. For setting to 2400 baud

;using a 10Mhs oscillator at a slow baud rate the formula

;is:

;At slow speed (BRGH = 0)

;---------- = ----------- = 2,403.84 (0.16% error)

return ;==============================

;transmit data ;==============================

;Test for Transmit Register Empty and transmit data in w SerialSend:

;==============================

;receive data ;==============================

;Procedure to test line for data received and return value

;in w. Overrun and framing errors are detected and

;remembered in the variable errorFlags, as follows:

;Bit 5 (RCIF) of the PIR1 Register is clear if the USART

;receive buffer is empty. If so, no data has been received

;At this point data has been received. First eliminate

;possible errors: overrun and framing.

;Bit 1 (OERR) of the RCSTA register detects overrun

;Bit 2 (FERR( of the RCSTA register detects framing error

;At this point no error was detected

;Received data is in the USART RCREG register

data

; Clear error flags

clrf errorFlags return

;error because FERR framing error bit is set

;can do special error handling here - this code simply clears

;============================================================

; I2C EEPROM data procedures

;============================================================

;GPRs used in EEPROM-related code are placed in the common

;RAM area (from 0x70 to 0x7f). This makes the registers

;accessible from any bank.

;============================