Z8F6421PM020SC Datasheet, PDF (123/299 Pages) Zilog, Inc. – High Performance 8-Bit Microcontrollers Z8 Encore-R 64K Series

Z8 Encore!^® 64K Series
Product Specification
103
Receiving Data using the Interrupt-Driven Method
The UART Receiver interrupt indicates the availability of new data (as well as error con-
ditions). Follow these steps to configure the UART receiver for interrupt-driven operation:
1. Write to the UART Baud Rate High and Low Byte registers to set the desired 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 Receiver interrupt and set
the desired priority.
5. Clear the UART Receiver interrupt in the applicable Interrupt Request register.
6. Write to the UART Control 1 Register to enable Multiprocessor (9-bit) mode
functions, if desired.
– Set the MULTIPROCESSOR Mode Select (MPEN) to Enable Multiprocessor
mode
– Set the MULTIPROCESSOR Mode Bits, MPMD[1:0], to select the desired
address matching scheme
– Configure the UART to interrupt on received data and errors or errors only
(interrupt on errors only is unlikely to be useful for Z8 Encore! devices without a
DMA block)
7. Write the device address to the Address Compare Register (automatic multiprocessor
modes only).
8. Write to the UART Control 0 register to:
– Set the receive enable bit (REN) to enable the UART for data reception
– Enable parity, if desired and if multiprocessor mode is not enabled, and select
either even or odd parity
9. Execute an EI instruction to enable interrupts.
The UART is now configured for interrupt-driven data reception. When the UART
Receiver interrupt is detected, the associated interrupt service routine (ISR) performs the
following:
1. Check the UART Status 0 register to determine the source of the interrupt - error,
break, or received data.
2. If the interrupt was caused by data available, read the data from the UART Receive
Data register. If operating in MULTIPROCESSOR (9-bit) mode, further actions may
be required depending on the MULTIPROCESSOR Mode bits MPMD[1:0].
3. Clear the UART Receiver interrupt in the applicable Interrupt Request register.
PS019915-1005
UART