Lindy 70918 user manual

4. You can select “Data Rate” change the crystal Frequency of input clock.

This page provides a list of common crystal values used with COM ports. Select “Detect crystal frequency” to detect the input clock frequency to the UART. (This requires that the port is not currently in use by another application).

The baud rate can optionally be adjusted according to the data rate required. To enable the advanced baud rate configuration options, deselect the “Use default baud rate” box. In normal operation, the driver will generate the desired baud rate from the crystal frequency. The quad speed option will multiply all application selected baud rates by 4 by utilising the OX16C95x Times clock register (TCR). The driver can multiply this baud rate, or divide it using the Clock Prescaler register (CPR).

The clock pre-divisor is used to divide the input clock prior to baud rate generation. This means a high speed crystal (e.g. 50MHz) can be pre-divided to generate standard baud rates (In this case 50 / 27.125 = 1.8433 MHz, which will emulate a 1.8432 MHz crystal with less than 0.01% bit rate error). Alternatively, the pre-divisor could be switched off to allow data rates up to 12.5Mbps to be generated.

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