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8XC196MC, MD, MH USER’S MANUAL
8-8
stb temp,freq_gen[0] ;into freq gen
ei ;enable interrupts
;
;
;*****************************************
; Now send buffer out as serial data bytes
;*****************************************
; This section issues a 1 millisecond pulse on P2.0
; for use with an oscilloscope monitor.
;*****************************************
;
ld wsr,#7EH
ld temp,#0400
andb p2_reg_w,#11111110b ;strobe p2.0 to sync
andb p2_dir_w,#11111110b ;scope
andb p2_mode_w,#11111110b;
orb p2_reg_w,#00000001b ;set pin high
djnzw temp,$ ;pause
andb p2_reg_w,#11111110b ;set pin low
ld wsr,zero_reg
;*****************************************
; Initialize the buffers and flag register that the interrupt routine needs.
;*****************************************
;
ld buf_start,#xmit_buf ;pointer reg
ld buf_cnt,#buf_size ;number to send
ldb flag,#11000000b ;set “buffer send in progress”
; ;and “get next byte” flags
;*****************************************
; Set the compare module’s interrupt pending bit
; to start sending the buffer. Loop until the buffer
; send is complete, then start main program over.
;*****************************************
ldb int_pend1,#00000010b;force interrupt
wait: jbs flag,7,wait ;loop here until done
ljmp start ;then start over
;
;
;*******************************************
; COMPARE3 INTERRUPT ROUTINE
;*******************************************
; This routine executes each time the EPA compare channel times out.
; The “flag” register identifies the reason for the interrupt request.
;*******************************************
;
cseg at 0f120H ;comp3 Int vector demo board
;
pusha ;save cpu status
jbs flag,1,one_pause ;jump if one being sent
jbs flag,0,zero_pause ;jump if zero being sent
jbs flag,5,get_bit ;get next bit
jbs flag,6,get_byte ;get next byte
sjmp all_done ;if nothing set, done
;
get_byte: andb flag,#10111111b ;clear get byte flag
ldb shift_reg,[buf_start]+ ;get byte to send into temp
ldb bit_cnt,#8 ;# of bits to send per char