Dangerous Prototypes

Hi everyone, I decided to post this small project, it's just a board to use the FT232BL chip with a 3.3V regulator, so you can be able to use it with 5V or 3.3V logic level. Any suggestion is welcome.

Pictures would be nice! :P

Some of don't have eagle installed so we can't open and view the schematic or board files. :(

Hi ginpb, I've modified your board design so that no VCC lines goes downside the USB connector, because a risk of short is there. I've also modified few other things. Check it.

Its a good layout,but I'm concerned about the proximity of R6,R7 and C5 to the chip.Also,the track from pin 3 of IC2 can be made straight off pin 3,rather than that 90 bend.
Having made my first board recently,this is one thing I realized,i.e not to keep things so tight,cuz without soldermask,shorts could come up easily.

For the windows impaired I submit images.

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It might also be a good idea to add ground to the output IO as well as the power supply pin

i noticed you did route some traces between the pads of resistors or capacitors. That can give some problems when etching at home.

Glad to see that you appreciate this small project, thanks to all of you who have taken a moment to look and correct my work.

Sjaak, initially i was concerned about putting traces under 0603 parts, but after i made some boards with traces under 0603 parts I can said that is possibile and not difficult at all do it at home, (I'm using a laser printer with a resolution of 600dpi).
Arakis, I don't put power pins at the IO connectors just because the 3.3 LDO can submit only 150ma so i can imagine what you could attach to that.
Arupbsk, thanks for the modifications.
One last thing the eeprom is not necessary, is an optional, the board can be smaller without it.

This is just a small modification of the board Arupbsk mod.

Nice Ginpb,
See your project featured in DP. http://dangerousprototypes.com/2012/01/ ... t-signals/ (http://dangerousprototypes.com/2012/01/09/simple-usb-to-uart-adapter-that-works-with-3-3v-and-5v-uart-signals/)
Forgot to tell you that DRC reports 100+ errors for fonts, silkscreen etc. But those aren't any issue for homemade TT PCBs.

You are still going to need a ground reference on the pin header that connects to the outside world or the link won't work.  were you planning to connect ground to the target device some other way?

Dolabra you have absolutely right, we need a ground pin, rookie mistake.
Arakis of course you have right

This is a reviewed version, contrary to what I said before I added VCC and GND.

another thought :)  should you make the pinout compatible with standard FTDI cables?  You are bringing out more signals, which is cool, but you could make the standard ones in the same order.  I realize that it will make your routing more challenging.

it's possible, as i don't own FTDI cables I made it to be easy to route, but if you send me the FTDI cable pinout I can modify my circuit.

It's up to you..... I was just thinking that several arduino-ish  things have that pinout so it might make it easier to hook your thing up to target boards.  There are a couple variation of the "standard" this looks like a pretty good discussion of the differences: http://diydrones.com/profiles/blogs/ard ... tool-fixed (http://diydrones.com/profiles/blogs/ardupilot-config-tool-fixed)

• FT232B is obsolete. Use FT232R instead. It is the one recommended for new designs.
• FT232R have an integrated EEPROM, so it will even save you component count.
• No need to use the additional regulator, both of them have integrated 3.3V regulator.

sobh,
1)it's true, but i have a couple of ft232BL on my drawer, so....
2)The eeprom it's not necessary, it's an optional.
3)I don't know about the FT232R, but the integrated 3.3V regulator can supply just a few mA and can be not enough. It's written on the datasheet.

I've made a small PCB for a FT232R with two jumpers:
-first chooses VDDIO between the internal 3.3 and 5V usb
-second connects VDDIO to the 4 pin header VCC pin.

The first jumper allows me to select 3.3 or 5V for the serial interface, the most used ones.
The second jumper allows me to supply my circuit with power(5 or 3.3) or to power VDDIO from my circuit(by removing jumper one).

do you build the PCB i've posted?
You still have a 3.3 V regulator?

If it's relevant, here's what I did for myself. Attached are schematics, board layout and pictures of an assembled device.

Features are:
-Jumper-selected slave scheme voltage: 5V or 3,3V (50mA max)
-RTS is out (with a wire cutting, can be changed to DTR)
-LEDs for Rx and Tx
-Three GPIO broken out (one has a pull-up)
-Two pinouts - one is Arduino Pro, another one I've been using for long...

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Hi dchcaracter,

What is that red material covering the cable on the opposite side of the USB connector? Is it standard heatsink or some other material?

Thanks!

I guess it's standard heat shrink tube.

Yes, that's a heat shrink tube. It has a disadvantage however - it cover's all the pinout cheat labels, so I had to cut a window for them from the bottom.

Eagle files also