[time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812A GPSDO system
Brooke Clarke
brooke at pacific.net
Tue Nov 4 19:58:13 UTC 2014
Hi Hal:
Yes for level shifting. Most micro controllers have the UART built-in so that's all that's needed.
I haven't got my boxes so don't know what chips are in them.
Mail_Attachment --
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
http://www.prc68.com/I/DietNutrition.html
Hal Murray wrote:
> brooke at pacific.net said:
>> UARTs are not mandatory, a simple transistor level shifting circuit is all
>> that's needed for TTL/RS-232 levels.
> I think you are confusing UARTs with level shifters.
>
> In the old days, transistors were expensive enough that a 68000 class CPU was
> all that could fit on a chip. All memory and peripherals were off chip.
>
> While not quite mandatory, most of the time it made sense to use a UART chip.
> If you had a FPGA, you could put a simple UART in there. (But back then,
> FPGAs weren't very big either.) If the CPU was idle, you could bit-bang
> things.
>
>
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