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View Full Version : Beginners issue: Prop plug vs Sparkfun FTDI 3.3 Breakout - are there any differ



Micrathene
05-19-2010, 05:17 AM
Hiya

First attempt at posting on a forum, but anyway - here's a bit of background I've been interested in microcontrollers for a while, and took the plunge with the bloggers favourite, the arduino, so I invested in some basic kit for that, including the Sparkfun FTDI breakout board.

Then I read about the prop, which seems generally more powerful, with some extra nonstandard hardware (like the built in video generators etc), and after a look round the object exchange, thought I'd have a go. Because I'd bought some other microcontrollers and had a (basic) play around with simple sensors, LCD displays, voltage regulators and so on, I thought I could bypass the need for a propeller proto board, and just start out with the chips and build my own support circuit. So I got a couple of props, and I spent a chunk of last weekend attempting to get started. I'm sure I'm supplying the correct pins on the prop with regulated 3.3v power and ground, but I couldn't get the propeller tool to recognise the chip.

Is this because I'm using the sparkfun breakout board I'd already purchased instead of the prop plug? My logic was that it shouldn't matter, as they both use the same FTDI chip anyway? Are there any settings or drivers that specifically need to be altered to use other FTDI breakout boards with the propeller tool?

For what it's worth, I had the chip set up as shown here http://www.instructables.com/id/Programming-the-Propeller-Microcontroller/step2/Hardware-Setup/.

Sorry if this is a common issue, but I had a search of the forums and the web generally and it doesn't look like anyone has specifically addressed this issue, though many peopel seem to have had success with using other usb to serial converters, they just don't post the specifics.

Thanks!

Rayman
05-19-2010, 07:08 AM
You need the DTR pin to control the Prop's reset line in order for the Prop tool to recognize the Prop...

The problem with a lot of lower cost RS232 chips is that they don't provide the DTR signal...

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My Prop Info&Apps: ·http://www.rayslogic.com/propeller/propeller.htm

My Prop Products:· http://www.rayslogic.com/Propeller/Products/Products.htm

Nick McClick
05-19-2010, 07:17 AM
Hey Micrathene -
1 - Welcome to the Propeller! I think you'll have a lot of fun. Awesome to see you started with my instructable!

2 - I'm not familiar with the Sparkfun FTDI board. Is it This one (http://www.sparkfun.com/commerce/product_info.php?products_id=8772)? If so, it looks like DTR is broken out, but it's in a different pin position. Did you re-wire it so the DTR on the FTDI board is connected to RST on the prop?

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Bill Henning
05-19-2010, 07:31 AM
Download the schematic of the demo board.

You will see the one transistor, two resistor, one capacitor circuit added to the DTR output line from the FTDI chip to turn it into /RESET for the propeller.

Add that, and everything should work :)


Micrathene said...
Hiya

First attempt at posting on a forum, but anyway - here's a bit of background I've been interested in microcontrollers for a while, and took the plunge with the bloggers favourite, the arduino, so I invested in some basic kit for that, including the Sparkfun FTDI breakout board.

Then I read about the prop, which seems generally more powerful, with some extra nonstandard hardware (like the built in video generators etc), and after a look round the object exchange, thought I'd have a go. Because I'd bought some other microcontrollers and had a (basic) play around with simple sensors, LCD displays, voltage regulators and so on, I thought I could bypass the need for a propeller proto board, and just start out with the chips and build my own support circuit. So I got a couple of props, and I spent a chunk of last weekend attempting to get started. I'm sure I'm supplying the correct pins on the prop with regulated 3.3v power and ground, but I couldn't get the propeller tool to recognise the chip.

Is this because I'm using the sparkfun breakout board I'd already purchased instead of the prop plug? My logic was that it shouldn't matter, as they both use the same FTDI chip anyway? Are there any settings or drivers that specifically need to be altered to use other FTDI breakout boards with the propeller tool?

For what it's worth, I had the chip set up as shown here http://www.instructables.com/id/Programming-the-Propeller-Microcontroller/step2/Hardware-Setup/.

Sorry if this is a common issue, but I had a search of the forums and the web generally and it doesn't look like anyone has specifically addressed this issue, though many peopel seem to have had success with using other usb to serial converters, they just don't post the specifics.

Thanks!

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www.mikronauts.com (http://www.mikronauts.com) E-mail: mikronauts _at_ gmail _dot_ com
My products: Morpheus (http://mikronauts.com/products/morpheus/) / Mem+ (http://mikronauts.com/products/morpheus/memplus/) / PropCade (http://forums.parallax.com/showthread.php?p=894725) / FlexMem (http://forums.parallax.com/showthread.php?p=894853) / VMCOG (http://forums.parallax.com/showthread.php?p=878382) / Propteus (http://mikronauts.com/products/propteus/) / Proteus (http://mikronauts.com/products/proteus/) / SerPlug (http://mikronauts.com/products/serplug/)
and 6.250MHz Crystals to run Propellers at 100MHz (http://mikronauts.com/products/mikronauts-625mhz-crystal/) & 5.0" OEM TFT VGA LCD modules (http://forums.parallax.com/showthread.php?p=852195)
Las (http://mikronauts.com/software-products/largos/) - Large model assembler Largos (http://mikronauts.com/software-products/largos/) - upcoming nano operating system

Karl Smith
05-19-2010, 07:43 AM
I did just what Bill Henning said to one these boards, its only $14.00

http://www.moderndevice.com/products/usb-bub

Robofreak
05-19-2010, 07:43 AM
I build my serial communication circuits directly into the board using one of Parallax's older schematics. I simply connect the DTR pin to the Prop's reset pin through a 0.1uf capacitor in series, and it works perfectly ;) I would try that before adding transistors and resistors, but it's up to you. I'm sure the transistor circuit is somewhat safer and more reliable though hah

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Austin Bowen,


"One must watch out for mechanics. They start out with a sewing machine, and end up with the atomic bomb" - A quote from someone that I saw on Addall.com

"Not only do I see the glass as half empty, I wonder if anyone poisoned the glass with arsenic" - My dad, inside joke haha

Micrathene
05-20-2010, 12:53 AM
Great, I'll be sure to try these out over the weekend - I work away during the week. Thanks for the quick replies!

Micrathene
05-22-2010, 10:45 PM
Thanks, I used the capacitor, resistor transistor combo copied from the demo board, and everything worked this time round. How do most people protype and experiment with the prop? I can imagine that high frequencies from the crystals, or those generated for video don't work very well on standard protoboards. I assembled this circuit together on some veroboard, which takes a lot longer. Is it possible to attach standard headers and use quick protoboards on leads off of these headers - or does that then lead to issues with voltage drops, capacitance and inductance (I know these can mess up waveforms etc, but not quite sure how severe the effects are).

Are there any suggestions for crystals for use with the prop? And after a hunt around the schematics I notice that the 24lc I2C eeproms are used to store boot code on quite a few boards - will most i2c eeproms work with the prop's bootcode, or is the 24lc a specifically blessed eeprom, as it were.

Sorry for the random assortment of questions, but thanks for the help - I've built my own proto board (sort of) and didn't need to spend the extra for a prop plug! Attached is a photo of the working circuit :), with the ftdi breakout board next to it.

DogP
05-24-2010, 09:49 AM
It looks like you got it taken care of, but the newer versions of the Prop tool support selecting DTR and/or RTS for the reset signal (in the preferences). I used that when I used the FTDI MM232R (which I had a few of laying around).

Pat