Table of Contents
Advertisement
12
12.5 Precautions on Using CSIO Mode
• Settings of SIO Transmit/Receive Mode Register and SIO Baud Rate Register
The SIO Transmit/Receive Mode Register and SIO Baud Rate Register and the Transmit Control
Register's BRG count source select bit must always be set when not operating. When transmitting
or receiving data, be sure to check that transmission and/or reception under way has been
completed and clear the transmit and receive enable bits before you set the registers.
• Settings of Baud Rate (BRG) Register
If you selected f(BCLK) with the BRG clock source select bit, make sure the BRG register value you
set does not exceed 2 Mbps.
• About successive transmission
To transmit multiple data successively, set the next transmit data in the SIO Transmit Buffer
Register before transmission of the preceding data is completed.
• About reception
Because during CSIO mode the receive shift clock is derived from operation of the transmit circuit,
you need to execute transmit operation (by sending dummy data) even when you only want to
receive data. In this case, note that if the port function is set for TXD pin (by setting the operation
mode register to 1), dummy data is actually output from the pin.
• About successive reception
To receive multiple data successively, set data (dummy data) in the SIO Transmit Buffer Register
before the transmitter starts sending data.
• Transmit/receive operations using DMA
To transmit/receive data in DMA request mode, enable the DMAC to accept transfer requests (by
setting the DMA Mode Register) before you start serial communication.
• About the receive-finished bit
If a receive error (overrun error) occurs, the receive-finished bit cannot be cleared by reading out
the receive buffer register. In this case, it can only be cleared by clearing the receive enable bit.
12.5 Precautions on Using CSIO Mode
12-43
SERIAL I/O
Ver.0.10
Advertisement
Table of Contents
