Guard Time And Prescaler Register (Usart_Gtpr) - ST STM32F101xx Reference Manual

Universal synchronous asynchronous receiver transmitter (USART)
27.6.7

Guard time and prescaler register (USART_GTPR)

Address offset: 0x18
Reset value: 0x0000
31 30 29
15 14 13
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Bits 31:16 Reserved, forced by hardware to 0.
Bits 15:8 GT[7:0]: Guard time value
This bit-field gives the Guard time value in terms of number of baud clocks.
This is used in Smartcard mode. The Transmission Complete flag is set after this guard time
value.
This bit is not available for UART4 & UART5.
Bits 7:0 PSC[7:0]: Prescaler value
– In IrDA Low-power mode:
PSC[7:0] = IrDA Low-Power Baud Rate
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):
00000000: Reserved - do not program this value
00000001: divides the source clock by 1
00000010: divides the source clock by 2
...
– In normal IrDA mode: PSC must be set to 00000001.
– In smartcard mode:
PSC[4:0]: Prescaler value
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:
00000: Reserved - do not program this value
00001: divides the source clock by 2
00010: divides the source clock by 4
00011: divides the source clock by 6
...
Note: Bits [7:5] have no effect if Smartcard mode is used.
This bit is not available for UART4 & UART5.
800/1096
28 27 26 25
12 11 10 9
GT[7:0]
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Doc ID 13902 Rev 12
24 23 22 21
Reserved
8 7 6 5
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20 19 18 17
4 3 2 1
PSC[7:0]
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RM0008
16
0
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