MC81F4432
Mode 0 Transmit Procedure
1. Set Rx/Tx pins to Alternative mode.
2. Set the baud rate
- Select the UART clock by setting the UCLK(UCONL.[3-2]) bits.
- Set the BRDAT register properly
3. Select mode 0 by setting the USM(UCONH.[7-6]) bits.
4. Write transmission data to the UDA.
After finish above steps, the data transmission will be started. And after finish the transmission, both
UTIR(IRQL.3) and UTIF(INTFL.0) bits are set to „1‟ by hardware.
Mode 0 Receive Procedure
1. Set the baud rate
- Select the UART clock by setting the UCLK(UCONL.[3-2]) bits.
- Set the BRDAT register properly
2. Select mode 0 by setting the USM(UCONH.[7-6]) bits.
3. Clear the receive interrupt request flag bit URIR(IRQL.4).
4. Set the SDR(UCONH.4 / UART receive enable bit) by „1‟.
Right after finish above steps, the shift clock will be output to the TxD (R15) pin and receiving is
started at the RxD (R14) pin. After finish receiving, both URIR(IRQL.4) and URIF(INTFL.1) bits are set
to "1" by hardware.
Uart Mode 1
Tx
Clock
Write to Shift Register (UDAT)
Shift
TxD
D0
D1
D2
D3
D4
D5
D6
D7
Stop Bit
Start Bit
UTIR
Rx
Clock
RxD
D0
D1
D2
D3
D4
D5
D6
D7
Stop Bit
Start Bit
Bit Detect Sample Time
Shift
URIR
Figure 24-3 Timing Diagram for UART Mode 1 Operation
October 19, 2009 Ver.1.35
153
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