Z8 Encore! XP
®
4K Series
Product Specification
92
6. Check the
TDRE
bit in the UART Status 0 register to determine if the Transmit Data
register is empty (indicated by a 1). If empty, continue to Step 6. If the Transmit Data
register is full (indicated by a 0), continue to monitor the TDRE bit until the Transmit
Data register becomes available to receive new data.
7. Write the UART Control 1 register to select the outgoing address bit.
8. Set the Multiprocessor Bit Transmitter (MPBT) if sending an address byte, clear it if
sending a data byte.
9. Write the data byte to the UART Transmit Data register. The transmitter automatically
transfers the data to the Transmit Shift register and transmits the data.
10. Make any changes to the Multiprocessor Bit Transmitter (
MPBT
) value, if appropriate
and MULTIPROCESSOR mode is enabled,.
11. To transmit additional bytes, return to Step 5.
Transmitting Data using the Interrupt-Driven Method
The UART Transmitter interrupt indicates the availability of the Transmit Data register to
accept new data for transmission. Follow these steps to configure the UART for interrupt-
driven data transmission:
1. Write to the UART Baud Rate High and Low Byte registers to set the appropriate baud
rate.
2. Enable the UART pin functions by configuring the associated GPIO Port pins for
alternate function operation.
3. Execute a DI instruction to disable interrupts.
4. Write to the Interrupt control registers to enable the UART Transmitter interrupt and
set the acceptable priority.
5. Write to the UART Control 1 register to enable MULTIPROCESSOR (9-bit) mode
functions, if MULTIPROCESSOR mode is appropriate.
6. Set the MULTIPROCESSOR Mode Select (MPEN) to Enable MULTIPROCESSOR
mode.
7. Write to the UART Control 0 register to:
–
Set the transmit enable bit (TEN) to enable the UART for data transmission
–
Enable parity, if appropriate and if MULTIPROCESSOR mode is not enabled, and
select either even or odd parity.
–
Set or clear
CTSE
to enable or disable control from the remote receiver using the
CTS pin.
8. Execute an EI instruction to enable interrupts.
PS022815-0206
UART
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