Quatech DSC-200/300 user manual Force High-Speed Uart Clock X2, X4, or X8, J10-J12

2.4.2 Force High-Speed UART Clock (X2, X4, or X8, J10-J12)

These jumpers force an increase of the UART input clock frequency by a factor of two, four, or eight. This feature can allow legacy software to use baud rates above 115,200 bits per second. It is also useful if the serial port device driver does not directly support setting the higher baud rates through the Options Register (see page 10).

If one of these jumpers is applied, it overrides any value written to the Options Register to set the clock multiplier by software. The effective baud rate will be either two, four, or eight times the value for which the UART itself is programmed.

The factory default is none of these jumpers applied, which allows for software control of the clock multiplier via the Options Register. The Options Register powerup default is for a standard times-1 clock of 1.8432 MHz for compatibility with standard serial ports.

J10	X2	J10	X2
J11	X4	J11	X4
J12	X8	J12	X8
J13	SPAD	J13	SPAD
Factory default		Force times-two clock
software control		Baud rates up to 230.4 kbps
J10	X2	J10	X2
J11	X4	J11	X4
J12	X8	J12	X8
J13	SPAD	J13	SPAD
Force times-four clock		Force times-eight clock
Baud rates up to 460.8 kbps		Baud rates up to 921.6 kbps

Figure 5 --- Clock multiplier jumper options

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