Epson S1C63558 4.10.7 Transfer rate setting for serial interface

CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Programmable Timer)

4.10.7 Transfer rate setting for serial interface

The signal that is made from underflows of timer 1 by dividing them in 1/2, can be used as the clock source for the serial interface.

The programmable timer outputs the clock to the serial interface by setting timer 1 into RUN state (PTRUN = "1"). It is not necessary to control with the PTOUT register.

PTRUN1

Timer 1 underflow

Source clock for serial I/F

Fig. 4.10.7.1 Synchronous clock of serial interface

A setting value for the RLD1X register according to a transfer rate is calculated by the following expres- sion:

RLD1X = fosc / (32 ∗ bps ∗ division ratio of the prescaler) - 1 fosc: Oscillation frequency (OSC1/OSC3)

bps: Transfer rate

(00H can be set to RLD1X)

Be aware that the maximum clock frequency for the serial interface is limited to 1 MHz when OSC3 is used as the clock source.

70 EPSON S1C63558 TECHNICAL MANUAL