FUJITSU Semiconductor Controller MB89950/950A - Manual (Page 228)

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CHAPTER 10 UART
Table 10.4-4 Serial mode control register 2 (SMC2) bits
Bit Function
Bit 7
Bit 6 Unused bits • The read value is indeterminate.
• Writing to these bits has no effect on the operation.
Bit 5 PSEN:
Operation enable bit • This bit enables baud rate generator. Baud rate generator is stopped by writing "0" to
this bit after transmitting/receiving the current serial data, then disabled thereafter.
Bit 4 Reserved bit • Always write "0".
Bit 3 RSEL:
UART/SIO selection
bit • The bit is used to select whether the UART or serial I/O uses the data and clock I/O
pins.
Bit 2 Unused bit • The read value is indeterminate.
• Writing to this bit has no effect on the operation.
Bit 1
Bit 0 PDS1, PDS0:
Input clock divider
selection bits • These bits are used to select the clock prescaler of the baud rate generator.