668-0011 Rabbit Semiconductor, 668-0011 Datasheet - Page 137

• Manufacturer Part Number: 668-0011
• Description: IC MPU RABIT3000A 55.5MHZ128LQFP
• Manufacturer: Rabbit Semiconductor

Specifications of 668-0011

• Rohs Status: RoHS non-compliant
• Processor Type: Rabbit 3000 8-Bit
• Speed: 55.5MHz
• Voltage: 2.5V, 2.7V, 3V, 3.3V
• Mounting Type: Surface Mount
• Package / Case: 128-LQFP
• Features: -
• Other names: 316-1043

17.3 Operation
17.3.1 Asynchronous Mode
The following steps explain how to set up Serial Ports A – D for asynchronous operation.
The serial ports can be used by polling the status byte, but their performance will be better
with an interrupt. These instructions also apply to the asynchronous operation of Serial
Ports E – F.
1. Write the interrupt vector for the interrupt service routine to the internal interrupt table.
2. Set up the desired transmit pin by writing to the appropriate parallel port function register
3. Select the appropriate mode by writing to SxCR (receive input port and 7 or 8 bits).
4. Select additional options by writing to SxER (parity, RZI encoding, clock polarity, and
5. Write the desired divider value to TATxR for the appropriate serial port.
A sample asynchronous serial interrupt handler is shown below for Serial Port A.
To transmit with an address (1) bit appended, write the data to SxAR instead of SxDR; to
append a long stop (0) bit write to SxLR instead.
Chapter 17 Serial Ports A – D
(PCFR or PDFR).
Also select the interrupt priority.
behavior during break).
async_sera_isr::
rx_ready:
check_for_tx:
done:
push af
ioi ld a, (SASR)
bit 7,a
push af
jr
ioi ld a, (SADR)
; do something with byte here
pop af
bit 3,a
jr nz, done
; get next byte to be transmitted into A here
ioi ld (SADR), a
pop af
ipres
ret
z, check_for_tx
; save used registers
; get status
; check if byte ready in RX buffer
; save status for next check
; read byte and clear interrupt
; check if TX buffer was emptied
; load next byte into TX buffer and clear interrupt
; restore used registers
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