PC COM port to Vic interfacing

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SparkyNZ
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PC COM port to Vic interfacing

Postby SparkyNZ » Thu Nov 16, 2017 7:48 pm

What is the easiest way to interface a PC COM port to a Vic? I've seen plenty of RS232-TTL converters on Aliexpress with DB9 connectors on one side, 4 pins on the other with VCC, GND, TX and RX. Would I be able to use one of these and wire up the 4 pins to the Vic's user port?

I've done heaps of RS232 comms/serial programming in Windows and I'd like to have a play with talking to one of my Vics.

What baudrate would I be able to use - 1200baud max?

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srowe
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Re: PC COM port to Vic interfacing

Postby srowe » Fri Nov 17, 2017 1:53 am

Yes, these modules will work ok, although mine didn't last very long and I ended up building my own. Max baud rate, depends on what you are using on the VIC. There's no working hardware flow control by default.

groepaz
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Re: PC COM port to Vic interfacing

Postby groepaz » Fri Nov 17, 2017 7:44 am

you pretty much want one that has RTS/CTS wired up - i'd just look (eg on jim brains site) for a c64 userport rs232 interface, it should work on vic20 too

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SparkyNZ
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Re: PC COM port to Vic interfacing

Postby SparkyNZ » Mon Nov 20, 2017 11:57 pm

groepaz wrote:you pretty much want one that has RTS/CTS wired up - i'd just look (eg on jim brains site) for a c64 userport rs232 interface, it should work on vic20 too


Thanks for the responses guys. Been a little busy to get round to playing with this yet (and I have to wait for the TTL/232 converters to arrive).

Do you really need the RTS CTS pins? The reason I ask is that I've never had to bother with hardware flow control for the past 15 years on the various projects I've worked on. Modems seemed to be the only devices that I found ever needed them. Is the communicating with the Vic more fiddly with it being older hardware? Perhaps it can't buffer as much data as modern devices so you need the flow control?

It was a silly idea, but I thought about driving the Vic to play music from my PC tracker program :) Sure, the Vic doesn't have a SID and is pretty simple sounding but I thought it could be a laugh to stream simple music commands to the Vic.

groepaz
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Re: PC COM port to Vic interfacing

Postby groepaz » Tue Nov 21, 2017 11:00 am

the hardware flow control is essential for slow devices (like the VIC20, or any other 8bit computer for that matter). thats pretty much the reason for why it exists :)

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SparkyNZ
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Re: PC COM port to Vic interfacing

Postby SparkyNZ » Tue Nov 21, 2017 12:56 pm

groepaz wrote:the hardware flow control is essential for slow devices (like the VIC20, or any other 8bit computer for that matter). thats pretty much the reason for why it exists :)


Would something like this do the trick? This has CTS and DTR pins - no RTS. From memory you don't connect CTS to CTS and RTS to RTS etc but I wouldn't know without further research.

https://www.aliexpress.com/item-img/TB196-5-5pcs-Pro-Mini-Download-USB-Programmer-RS232-TTL-Adapter-CTS-DTR-female-dupont-wire/32787840242.html#

groepaz
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Re: PC COM port to Vic interfacing

Postby groepaz » Tue Nov 21, 2017 6:13 pm

*shrug* how you connect them depends on their logic =P you cross rts/cts for nullmodem, but thats probably not what you got there. it makes sense to have only one of the two (the PC is kinda infinitely fast, the other side may be slow), but i forgot which goes in which direction =P

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Re: PC COM port to Vic interfacing

Postby wimoos » Wed Nov 22, 2017 8:46 am

VICE; selfwritten 65asmgen; tasm; maintainer of WimBasic

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srowe
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Re: PC COM port to Vic interfacing

Postby srowe » Fri Dec 08, 2017 11:15 am

SparkyNZ wrote:Would something like this do the trick? This has CTS and DTR pins - no RTS. From memory you don't connect CTS to CTS and RTS to RTS etc but I wouldn't know without further research.


No, the KERNAL routines expect double inversion of CTS, DTR, RTS, DSR, see the schematic of the VIC-1011 here

http://www.zimmers.net/anonftp/pub/cbm/schematics/cartridges/userport/1011005.gif


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