COP87L88RW Datasheet, PDF (25/42 Pages) National Semiconductor (TI) – 8-Bit One-Time Programmable OTP Microcontroller with Pulse Train Generators and Capture Modules

Baud Clock Generation
The clock inputs to the transmitter and receiver sections of
the UART can be individually selected to come either from
an external source at the CKX pin (port L pin L1) or from a
source selected in the PSR and BAUD registers Internally
the basic baud clock is created from the oscillator frequency
through a two-stage divider chain consisting of a 1 – 16 (in-
crements of 0 5) prescaler and an 11-bit binary counter (Fig-
ure 16) The divide factors are specified through two read
write registers shown in Figure 17 Note that the 11-bit Baud
Rate Divisor spills over into the Prescaler Select Register
(PSR) PSR is cleared upon reset
FIGURE 16 UART BAUD Clock Generation
TL DD 12855 – 16
FIGURE 17 UART BAUD Clock Divisor Registers
TL DD 12855 – 17
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