Serial Interface Configuration - Abov MC80F0304 User Manual

MC80F0304/08/16
RECEIVE
RxE
ACLK PIN
MUX 5-bit counter
XIN f ÷2 ~ f XIN ÷128
match (Divider) ÷2 Tx_Clock
Decoder
match ÷2
- TPS2 TPS1 TPS0 MDL3 MDL2 MDL1 MDL0 (Divider) Rx_Clock
(BRGCR)
5-bit counter
Internal Data Bus SEND TxE
Figure 16-2 Baud Rate Generator Block Diagram

16.2 Serial Interface Configuration

The UART interface consists of the following hardware. is received, one byte of new receive data is transferred from the
receive shift register (RXSR). When the data length is set as 7 bits, receive data is sent to bits 0 to 6 of RXR. In this case, the
Item Configuration MSB of RXR always becomes 0.
Transmit shift register (TXR) RXR can be read by an 8 bit memory manipulation instruction. It
Register Receive buffer register (RXR) Receive shift register cannot be written. The RESET input sets RXR to 00 H .
Serial interface mode register (ASIMR) Receive shift register
Control register Serial interface status register (ASISR) This register converts serial data input via the RXD pin to paral-
Baud rate generator control register (BRGCR) leled data. When one byte of data is received at this register can-
Table 16-1 Serial Interface Configuration not be manipulated directly by a program.
Asynchronous serial interface mode register
Transmit shift register (TXR) (ASIMR)
This is the register for setting transmit data. Data written to TXR This is an 8 bit register that controls UART serial transfer opera-
is transmitted as serial data. When the data length is set as 7 bit, bit 0 to 6 of the data written to TXR are transferred as transmit tion. ASIMR is set by a 1 bit or 8 bit memory manipulation in-
data. Writing data to TXR starts the transmit operation. 16-3 shows the format of ASIMR The RXD / R04 and TXD / truction. The RESET input sets ASIMR to 0000_-00- . Figure B
TXR can be written by an 8 bit memory manipulation instruction. R05 pin function selection is shown in Table 16-2.
It cannot be read. The RESET input sets TXR to 0FF H .
Receive buffer register (RXR) Note: transmit/receive operation has stopped. Do not switch the operation mode until the current serial
This register is used to hold receive data. When one byte of data
86 November 4, 2011 Ver 2.12