Timer Retrofit For Z80 SBCs

Description

The board itself is a simple clock generator using a 74HC4060 14 stage ripple counter. 2.45MHz goes in one end, 150Hz comes out the bottom. Along the way it generates a bunch of useful other clocks for serial ports.
Because almost all the SBC systems without timers seem to use Z80SIO or 16x50A UARTs there is no bus and interrupt line logic. Instead the 150Hz from the board can be fed into one of the modem control inputs and the UART itself provides both interrupt masking and control.

Files

timertick.kicad_pcb x-kicad-pcb - 68.81 kB - 11/09/2019 at 14:00		Download
timertick.sch x-kicad-schematic - 4.82 kB - 11/09/2019 at 14:00		Download

Components

1 × 74HCT4060 Logic ICs / Counters
1 × 0.1µF capacitor
1 × 8pin can oscillator to suit your needs
1 × Misc Headers
1 × Double sided sticky tab to stick onto sbc

Discussions

freefuel wrote 07/04/2023 at 00:59

Now that I've found this I'm reminded of a watchdog timer I have been thinking of, it was something along the lines of 2 to 4 32-bit programable counters running at 1x to some Nx divided down rate, when the timer trips it resets to it's programmed setting while outputting one of the z80 interrupts so it can be used in any of the three modes.

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Timer Retrofit For Z80 SBCs

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Description

Files

timertick.kicad_pcb

timertick.sch

Components

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