12
12-62
Ver.0.10
SERIAL I/O
12.9 Precautions on Using UART Mode
12.9 Precautions on Using UART 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 is equal to or greater than 7.
The value written to the SIO Baud Rate Register becomes effective beginning with the next period
after the BRG counter finished counting. However, when transmit and receive operations are
disabled, the register value can be changed at the same time you write to the register.
• 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 overrun error
If all bits of the next receive data are received in the SIO Receive Shift Register before you read out
the SIO Receive Buffer Register (an overrun error occurs), the receive data is not stored in the
Receive Buffer Register and the Receive Buffer Register retains the previously received data.
Once an overrun error occurs, no receive data is stored in the Receive Buffer Register although
receive operation is continued. To restart reception normally, you need to temporarily clear the
receive enable bit before you restart. This is the only way you can clear the overrun error flag.
Summary of Contents for M32170F3VFP
Page 42: ...1 1 24 Ver 0 10 OVERVIEW 1 4 Pin Layout This is a blank page ...
Page 56: ...2 2 14 Ver 0 10 This is a blank page ...
Page 88: ...3 3 32 Ver 0 10 ADDRESS SPACE 3 7 Notes on Address Space This is a blank page ...
Page 270: ...9 9 40 Ver 0 10 DMAC 9 4 Precautions about the DMAC This is a blank page ...
Page 614: ...12 12 64 Ver 0 10 This is a blank page SERIAL I O 12 9 Precautions on Using UART Mode ...
Page 756: ...17 17 10 Ver 0 10 RAM BACKUP MODE 17 4 Exiting RAM Backup Mode Wakeup This is a blank page ...
Page 762: ...18 18 6 Ver 0 10 OSCILLATION CIRCUIT 18 2 Clock Generator Circuit This is a blank page ...
Page 831: ...CHAPTER 22 CHAPTER 22 TYPICAL CHARACTERISTICS 22 1 A D Conversion Characteristics ...
Page 833: ...Appendix 1 1 Dimensional Outline Drawing APPENDIX 1 APPENDIX 1 MECHANICAL SPECIFICATIONS ...
Page 841: ...Appendix 3 1 Precautions about Noise APPENDIX 3 APPENDIX 3 PRECAUTIONS ABOUT NOISE ...