Z8F0830HH020SG Datasheet, PDF (54/257 Pages) Zilog, Inc. – High-Performance 8-Bit Microcontrollers

Z8 Encore!^® F0830 Series
Product Specification
36
External Clock Setup
For systems using an external TTL drive, PB3 is the clock source for 20- and 28-pin
devices. In this case, configure PB3 for Alternate function CLKIN. Write to the Oscillator
Control Register (see the Oscillator Control Register Definitions section on page 154) to
select the PB3 as the system clock.
Table 16. Port Alternate Function Mapping
Port
Pin
Port A¹ PA0
Mnemonic
T0IN/T0OUT
Alternate Function Description
Timer 0 input/Timer 0 output complement
Alternate Function
Set Register AFS1
N/A
Reserved
PA1 T0OUT
Timer 0 output
Reserved
PA2 Reserved
Reserved
Reserved
PA3 Reserved
Reserved
Reserved
PA4 Reserved
Reserved
Reserved
PA5 Reserved
Reserved
Reserved
PA6 T1IN/T1OUT
Timer 1 input/Timer 1 output complement
Reserved
PA7 T1OUT
Timer 1 output
Reserved
Notes:
1. Because there is only a single alternate function for each Port A and Port D (PD0) pin, the Alternate Function
Set registers are not implemented for Port A and Port D (PD0). Enabling alternate function selections (as
described in the Port A–D Alternate Function Subregisters section on page 42) automatically enables the asso-
ciated alternate function.
2. Because there are at most two choices of alternate functions for any Port B pin, the AFS2 Alternate Function Set
Register is implemented but is not used to select the function. Additionally, alternate function selection (as
described in the Port A–D Alternate Function Subregisters section on page 42) must also be enabled.
3. Because there are at most two choices of alternate functions for any Port C pin, the AFS2 Alternate Function Set
Register is implemented but is not used to select the function. Additionally, alternate function selection (as
described in the Port A–D Alternate Function Subregisters section on page 42) must also be enabled.
PS025113-1212
External Clock Setup