Rainbow Electronics AT75C310 - Manual (Page 130)

AT75C310
130
tst rl, #OxO1
beq rx_poll_timed
ldr rl, USARTO_RHR_Reg
ldr r2, [r1]
mov pc, lr
;-----------------------------------------------------------------------------
; rx_poll
; Wait for a character to be received. The wait is not time limited
; Trashes rl, r2
;-----------------------------------------------------------------------------r
rx_poll
ldr rl, USARTO_CSR_Reg
ldr rl, [r1]
tst rl, #OxO1
beq rx_poll
ldr rl, USARTO - RHR_Reg
ldr r2, [r1]
mov pc, lr
;-----------------------------------------------------------------------------
; send-byte
; Wait for TXRDY then write the byte in r2
; Trashes rl
;-----------------------------------------------------------------------------s
send-byte
ldr rl, USARTO_CSR_Reg
ldr rl, [rl]
tst rl, #OxO2
beq send_byte
ldr rl, USARTO_THR_Reg
str r2, [r1]
mov PC, lr
;-----------------------------------------------------------------------------
; Fail Loop - If any problem that can't be solved arises in the code then
; branch to here.
;-----------------------------------------------------------------------------
fail-loop
B fail-loop
;-----------------------------------------------------------------------------
; remap - Code will jump here if there is a timeout on receiving the first
; byte of data, or there is an error in the initial sequence. Set the REMAP
; bit in the SIAP register, then set the PC to 0 - this will map in the memory at CSO
;-----------------------------------------------------------------------------
remap
ldr rl, SIAP_Mode_Reg
ldr r2, = OxO1
str r2, [rl]
mov PC, #OXOO
;-----------------------------------------------------------------------------
; USARTO Register Definitions
;-----------------------------------------------------------------------------
USARTO_CR_Reg
DCD OxFF018000
USARTO_MR_Reg
DCD OxFF018004
USARTO_ID_Reg