Interface with other USB-Serial chips

Chuck Davis

I am working on a product design for the propeller.· This product will be USB based but I will be using a USB to serial chip that is different from the one used in the Parallax products (Silicaon Labs CP2101 or CP2102).· This chip is USB 2.0 capable.

My question is: is there any reason I can't use this chip as an interface to program the Propeller?· It provides the same outputs (TX, RX, DTR), as well as a 3.3 volt, 100 ma regulator built in, which I would use to power the Prop.

Does the existing software depend in any way on the particular USB chip in use, or can it use this one as long as the drivers are installed and the appropriate COM port is configured?

Thanks for your help.

Chuck Davis

Mike Green

You should be able to use other USB to serial adapters and chips as long as the proper drivers are installed. The primary requirement is that they implement DTR and that they don't have long delays for the data and DTR signals. The only way to know for sure is to try it. The issue is that DTR is used to reset the Propeller and the RX/TX data lines are used for handshaking between the Propeller Tool and the Propeller with fairly tight timing at 115KBaud.

As of a couple of weeks ago, Silicon Lab's drivers did not include a Mac OS 10 driver for the Intel models. If you want good cross-platform support, FTDI is really the only way to go at this time.

Ariba

I have successfully used a CP2102 to connect to the Propeller. It was working well with Propeller Tools and PropTerminal.
But also the FT232R has an integrated 3.3V regulator (50mA for external devices).

Andy

Peter Jakacki

Hi Chuck,

I have used CP2102s in my Prop designs as well when I found at the time that the IDE didn't support it.
http://forums.parallax.com/showthread.php?p=636139

Well the guys at Parallax were very very good and sorted out the driver problems pronto, it turned out to be a bit of a Microsoft thing.

However my newer designs are using the FT232RQs as they are faster and just as simple to use as the CP2102s. The reason I had been using silabs parts was because they had been a much simpler solution compared to the earlier generation ftdi parts, but the FT232RQ bridged that gap.

*Peter*

Chuck Davis

Thanks for the input. After some consideration I decided it was simplest to use my existing USB chips for the application interface and add a prop clip connection for programming the propeller chip. This actually reduces the number of parts on the board, lets me use my existing parts and software drivers which are common to other products, lets me use separate pins for the application interface, and allows me to keep both the application and the programming interfaces connected while debugging. Only downside is the one-time cost of the prop clip, but I'm sure I'll use that for many other things in the future.

Chuck