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Topic: FT232RL on a standalone board (Read 2063 times) previous topic - next topic

nanohex

I sent off a PCB to be made for a project. It's basically an arduino with a couple of extras built in like a motor driver and LCD. However, when I test my FT232RL on a breadboard it doesn't even show up as a device :*! I think this has something to do with either the fact that I left the iron on WAY too long when trying to remove jumpers, or me being lazy and not bothering with any capacitors/inductors. Of course, when the PCBs arrive, I'll be much more careful, but in case the problem is with the actual connections, can somebody tell me if the schematic is right?

Thanks!  :)

Schematic: http://imgur.com/FoIJn

Graynomad

It's a very badly drawn schematic, but I think it's correct.

I wouldn't worry about the inductor, I've never seen anyone use it anyway. But you should have caps.

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Rob
Rob Gray aka the GRAYnomad www.robgray.com

pico


I wouldn't worry about the inductor, I've never seen anyone use it anyway.


Funny you should say that, I've just ordered a bunch to see if I can get better resolution using analogRead(). Easy and inexpensive experiment.
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westfw

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I've just ordered a bunch to see if I can get better resolution using analogRead().

They're talking about a different inductor (a ferrite bead on the USB power rail.  Uno and later Arduinos have this, I think.)

How sure are you about the pinout of your USB connector?  I notice that the schematic symbol you're using doesn't match the one from the official schematics, nor does it match the physical pinout (power is on the "outside" pins), and there have been issues (back in the diecimilla days) where the actual pinouts of the connectors were "confused."

nanohex

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It's a very badly drawn schematic, but I think it's correct.


Yeah, was my first attempt on doing something in Eagle :smiley-mr-green:! Glad it seems right though, spent hours trawling through the datasheet to make sure, as I've never used this chip before.

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How sure are you about the pinout of your USB connector?


I'm sure about the pinout, it's a USB-B receptacle. I checked the datasheet and used a multimeter, so no worries there!

Thanks for the help! Was worried sick that I screwed it up...

Graynomad

The trouble is there are no pin numbers on the USB socket, so there's no way to know if it's right or not. As drawn, and if one assumes the pins are in order, it doesn't appear to match the standard USB sockets.

The pins you show on the 232 chip do seem right, what happened to all the other pins?

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Rob
Rob Gray aka the GRAYnomad www.robgray.com

nanohex

This was the SparkFun "simple" FT232RL library part - said it only includes the pins that are needed for basic use (I don't care much for accessing the EEPROM on the chip and doing other fancy things - too hard right now  :smiley-sweat:). Just needed to check if the schematic will program an atmega328 like a normal arduino (the bootloader is already installed in the chip), just on a standalone board instead

Graynomad

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Just needed to check if the schematic will program an atmega328 like a normal arduino

In that case you need the 100nF cap on the DTR pin (pin 2) and connected to the reset signal.

Have a look at the Duemilanove schematic.

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

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