Author Topic: What kind of cable do I need for a PC to FPGA RS232 uart comm?  (Read 3634 times)

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Offline zdelarosa00Topic starter

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What kind of cable do I need for a PC to FPGA RS232 uart comm?
« on: November 11, 2016, 02:48:02 am »
This is the doubt, I need to implement a simple UART communication chain between my computer and my FPGA, the fpga its a chinese development board with a Cyclone I, and according to the datasheet (see attachement), the DB9 port that it has goes to a MAX232, wich to my understanding levels serial voltages to TTL. Then, my laptop doesn't have any serial ports (as does any from 8 years behind), so I'm thinking I need to buy a cable, but I dont know exactly wich of my options are, I've seen a couple (attachement), and I'm wondering, don't all these have a RS232 chip integrated? (or otherwise why would we need a driver cd right?), because some of them seem to not have the chip inside (white one on the attachement)..... Wich leads me to the main question, do I need to fabricate a usb to db9 breakout with no chips?, or the cable with the rs232 goes to the db9 on the board and then again to a rs232...?

This video illustrates it:
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Offline hamster_nz

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Re: What kind of cable do I need for a PC to FPGA RS232 uart comm?
« Reply #1 on: November 11, 2016, 06:21:06 am »
By an RS232 to 3.3V TTL cable from decent supplier and you should be fine. E.g. https://www.sparkfun.com/products/9873

The least fuss is usually those with and FTDI chip as Windows already has a driver.

 I prefer not to have a 5V/3.3V switch, because one day I will put 5V thorugh something that I didnt want to.
« Last Edit: November 11, 2016, 06:26:16 am by hamster_nz »
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Offline AndyC_772

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Re: What kind of cable do I need for a PC to FPGA RS232 uart comm?
« Reply #2 on: November 11, 2016, 08:54:51 am »
If it's got a MAX232 on board, then the cable needs to use real RS232 levels, not low level logic.

Google throws up many, many results for "USB RS232 cable". Pick one you can get locally.

Offline zdelarosa00Topic starter

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Re: What kind of cable do I need for a PC to FPGA RS232 uart comm?
« Reply #3 on: November 15, 2016, 01:35:01 am »
If it's got a MAX232 on board, then the cable needs to use real RS232 levels, not low level logic.

Google throws up many, many results for "USB RS232 cable". Pick one you can get locally.

So the usb to DB9 like this http://articulo.mercadolibre.com.mx/MLM-560978653-cable-adaptador-serial-macho-a-usb-20-macho-rs232-db9-_JM is the choice right?, today a professor at my college told me that RS232 its a protocol, so if Im receiving trought a 232 the signal needs to came already as 232 protocol.
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Offline zdelarosa00Topic starter

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Re: What kind of cable do I need for a PC to FPGA RS232 uart comm?
« Reply #4 on: November 15, 2016, 03:45:47 am »
The price is MXN thats why, it costs like 2 US dollars really  ;D .
I always get somehow confused at those serial protocols, good thing to know that about the Profilic driver!, I did have some trouble some months ago with a USB to TTL that I couldnt make work at plugnplay, but I will have to manage?, I think getting picky with that cheap cable chipsets its gonna be more pain than the stores can handle
Space landfill waste consultants say: "If you think you can or if you think you can't you're right" - Always on my way to be a better electronic wizard
 


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