Minima - CPU Module Mods

While building my Minima CPU module, and thinking about the circuit's programming interface components. I started wondering if there was an Off-the-Shelf USB product that could replace and simplify the circuit.

After a little research, I found three likely candidates, all available from Parallax.com;

• The Prop-Plug - $15
• The USB2SER - $14
• The 4D Systems USB Programmer - $20

Each have slightly different header pin-outs for connection to a project. Each uses the same FT232RQ USB-to-Serial chip.

For DYI, the FT232RQ chip is a simple "state machine", which does all of the hard work of USB-to-Serial protocol and signal-level translation. It is simple enough that it could be included directly into a project, all that is necessary is; the FT232RQ, a USB connector, and a few resistors (see the Prop-Plug datasheet with schematic). Note: Parallax encourages use of their schematic for DYI implementation, they will be happy to supply the parts, or as available elsewhere.

If the FT232RQ is included directly in a project, the +5V from the USB connector could also be used by the project, only the off-the-shelf 4D Systems USB Programmer (listed above) provides a fifth pin for a power connection.

The FT232RQ is available in the 28-LD-SSOP and the QFN-32 package. I will use the QFN-32, because I like smaller components. The price of the FT232RQ is about $5.00, but that is cheap for what it does and the components that it replaces.

Also, if the FT232RQ is included directly as part of a project, it is available for generic ASCII I/O for control or output via a standard USB connection.

Because I already have a Prop-Plug, I think I will simplify and re-layout the next Revision of my Minima CPU module with a simple Prop-Plug header. I hope this will work as a generic dumb download interface with the Arduino Interactive Development Environmnet (IDE), but this remain to be tested. Does anyone know?

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UPDATE: Apr 21, 2014 14:11
As per the comments, Larry has suggested the "FTDI Friend" - $15 from Adafruit.com

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WinradHD Running on Ubuntu 10.04 via Wine

Until recently I had been listening to my Softrock RX Ensemble on my one-and-only Windows XP Desktop Computer, all of my other computers have been converted to Ubuntu Linux.

Today I found out that "WinradHD" I/Q Decoder will run via "Wine" on Ubuntu 10.04. I have Ubuntu on my HP Pavilion Laptop, which has a Stereo Mic Input Jack (a surprise to me). The Laptop decodes the SDR I/Q signals very nicely, with a very low noise floor.

My initial test configuration used two computers; one (window XP) to changed the Ensemble LO Frequency via a USB connection, and the second (the laptop) to run WinradHD and provide audio output.

Then, via the Internet, I found the "usbsoftrock" deamon for Linux, which is a kind of driver/program for the Si570. It is like a command-line version of a combination of  "USB Driver", "CFGSR", and "SRDLL" as used on Windows XP, and  as previously described. Usbsoftrock runs on Ubuntu along with WinradHD.

Usbsoftrock allows changes to the Si570 frequency via a command-line command on the Ubuntu Laptop, for example:

$ usbsoftrock set freq 10.140

Status can be listed via:

$ usbsoftrock status

I need to find the magic to control the Si570 via "usbsoftrock" directly from "WinradHD" on Ubuntu. Using the keyboard to set a Frequency is not exactly fun.

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Note: A pre-compiled "usbsoftrock" Ubuntu package can be found as described on Steve Conklin, AI4QR web page and which was created by Jonathan, AF6YF (now N6JU) - Thanks Jonathan.

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USB Mini-B Connector Received

Just received the USB Mini-B connectors (P/N 538-54819-0572) from Mouser. Hopefully sometime soon I will have time to modify the artwork to include this connector for my Marker/Beacon/CW project. See previous post.

Project Connectors - Old USB Standard

The world of USB Connectors has gotten a whole lot bigger, or smaller, depending on your prospective.

I need a connector for a new project that I am planning. The connector must be as small as possible as there is very little space on a 1 x 1.2 inch PCB.

• On the PCB there will be; a stereo audio connector (for CW Keying), a push button switch, a crystal, and a 4 (or 5) pin connector which will occupy the majority of the space. The rest of the space will be used for; the Voltage Regulator and Decoupling Caps, 2N3904 RF Oscillator and Trimmer, PIC FSK Modulator, Status LED, Power Connector, and Antenna Connection. 

• Most of the resistors will be of size 0603, and cap's will be 0804 mils, most traces will be 8/8 mils.

Proposed Project

• The project is similar to my other 9 Volt Battery Frequency Markers, but this will be a smart QRSS Beacon. The required connector for; beacon mode, speed and message content programming. This thing will be used in stand-alone Beacon mode and casual interactive CW use.  My goals is to provide project documents so other, like minded people, can try their hand at this micro-circuit.

Why not make the PCB larger you ask?     Well, . . . I just like to make things as small as I can - just because I think I can.

The two connectors that I am considering using for this project are; the "Mini" or the "Micro" USB connectors. These are the smallest connectors that I have found. I know this will violate the "standards", by using them in this way, but it is my personal project and I will just have to not plug them into a standard USB fixture or cable.

In researching these connectors, I have learned a lot about the USB standards, and what that means for use with our smart phones and personal devices. A couple of things that I have learned are:

• We have China to thank for requiring the "standard" "Micro" charger and data transfer connectors on our new cell phones (and personal devices), they said make the charger standard or do not try to sell it in China (Why couldn't we have done that?). And yes, the standard is the new smaller "Micro" connector and not the "Mini" connector that is currently found on our "slightly" older personal devices.

• The first (and much larger) standard USB "A" and "B" connectors use four wires; +5 Volts, Gnd, +Data and -Data. The large flat "A" connector is normal found on the side of computers, and the smaller almost square "B" connector is normally used on peripherals. The connector establish the "Master/Slave" communication protocol.

USB A

Typically Found on Computers

USB B

Typically Found on Peripherals

• Adapters cables with one large "A" connector are available for connection to a second small "Mini" and "Micro" connectors. These smaller connectors have five (5) pins for connection, the first four (4) are the same as the larger USB "A" and "B" connectors, on some hardware the fifth pin is shorted to ground to indicate which device is to be, "Master" or "Slave" ( I don't remember the details of which is which). Also, the standard requires that only one data connector is allowed on any new personal device (Note, a second connector is allowed, but it can only be used for additional power). UPDATE: the new pin was added at position number 4, old pin 4 became pin five, see the wikipedia doc.

USB - Mini AB

Previous Generation Standard

USB - Mini B

Previous Generation Standard

Note: the Corner Notches

• The designators for these "Mini" and "Micro" connectors are "AB" and "B". The "AB" connector is rectangular and accepts both the "AB" and "B" male plugs, The "B" connector accepts the "B" plug and has corner notches as to reject the "AB" male plug.

• The current China Standard is the "Micro" connector (below) for all new personal devices. It is similar to the "Mini" connector (above), but about 1/2 the size (unlike the included drawings would imply).

USB - Micro AB

Current Standard

USB - Micro B

Current Standard

The good news is; because the USB connector is not only for data transfer, it also used for device battery "charging", so we now have a "auto and home" charging standard for personal devices - we are no longer condemned to multiple charger-cord hell. Now we have one charging cord plug standard for all new personal devices. I have been told that many new cars now have USB charging connectors as standard equipment.

The Current Standard
A, B and Micro

What does this mean for my project; "Mini" cables and Connectors are available in surplus and new stock, and because they are no longer new, and now a deprecated standard,  . . .  so now - I am going to use them in my projects!

This HomeBrew project (and similar follow-on projects) will be used as an Transmit Exciter for the QRP HF PA as planned in a previous post.

I will provide more details as my Home Brew Project continues.

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Note: For my future project reference, the Drawings and Photos were obtained from the Molex Catalog and Product Guides, at the following link:

http://www.molex.com/molex/products/group?key=usb_products&channel=PRODUCTS&langPref=english

The "Mini" and "Micro" USB connectors can be found on Mouser.com Catalog Page 1252

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