STM8S datasheet(374/467 Pages) STMICROELECTRONICS

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Universal asynchronous receiver transmitter (UART)

RM0016

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DocID14587 Rev 14

22.7.12

Prescaler register (UART_PSCR)

Address offset: 0x0A (UART1), 0x0B (UART2 and UART4)

Reset value: 0x00

Note:

Care must be taken to program this register with correct value, when both Smartcard and

IrDA interfaces are used in the application

654

3210

PSC[7:0]

Bits 7:0 PSC[7:0]: Prescaler value.

– In IrDA Low Power mode

PSC[7:0] = IrDA Low Power Baud Rate (1)

Used for programming the prescaler for dividing the system clock to achieve the low power

frequency:

The source clock is divided by the value given in the register (8 significant bits):

0000 0000: Reserved - do not program this value

0000 0001: divides the source clock by 1

0000 0010: divides the source clock by 2

...

– In Smartcard mode

PSC[4:0]: Prescaler value. (2) (3)

Used for programming the prescaler for dividing the system clock to provide the smartcard clock.

The value given in the register (5 significant bits) is multiplied by 2 to give the division factor of the

source clock frequency:

0 0000: Reserved - do not program this value

0 0001: divides the source clock by 2

0 0010: divides the source clock by 4

0 0011: divides the source clock by 6

...

Note: These bits are not available for UART3.

1. This prescaler setting has no effect if IrDA mode is not enabled.

2. This prescaler setting has no effect if Smartcard mode is not enabled.

3. Bits [7:5] have no effect even if Smartcard mode is enabled.

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