The MiniGen Signal Generator is a small board capable of generating sine, square, or triangle waves at up to 3MHz, and approximately 1Vp-p. Although the MiniGen was designed as a shield for the Arduino Pro Mini, it also can operate as a stand-alone board.

The MiniGen offers two output sources: a 2-pin 0.1"-spaced header and a U.FL connector. The output is at a DC offset of Vcc/2, however neither the offset nor the amplitude can be varied. By default, the MiniGen ships configured with a 3.3V regulator enabled and should only be used with 3.3V signals (or 3.3V Pro Minis if you are using this as a shield). A solder jumper on the back can be placed to bypass the regulator so you can use this on a 5V Pro Mini or other 5V system — just make sure you then provide a regulated 5V supply or you will damage the MiniGen!

This board does not come with headers. Here are some options that you can solder onto the board:

• Strip of 40 header pins — can be broken down to the required sizes.
• 6-pin stackable female header — use four of them to populate the two 12-pin rows.
• Right-angle header pins — since only one side of the MiniGen needs to be connected (see below), these pins give you a side-mounted option in case you're using it with something other than an Arduino Pro Mini.

MiniGen Signal Generator Board Features

• 10-bit DAC for good accuracy
• Two frequency registers
• Two phase registers
• SPI driven at 40 MHz
• Operating voltage: 3.3V by default; 5V possible when solder jumper is placed

MiniGen Pinout

• GND — Only one of these needs to be connected at a time. This means you can get away with headers on one side only if that suits your application better.
• VIN — By default, this goes to a 3.3V regulator. If you want to use the board with a 5V Pro Mini, you should put a blob of solder on the jumper pads on the back to connect all three together. Just be aware that you'll then be bypassing the regulator, so you must not apply more than 5V to the board.
• SCLK — SPI clock input. The SPI bus can handle up to 40MHz input.
• SDATA — Input from the master device. Note that register contents cannot be read out from the AD9837 part; it lacks a DOUT pin.
• FSYNC — Equivalent to Chip Select.
• OUTPUT- — Connected to ground.
• OUTPUT+ — This is the anti-aliased output from the AD9837. Expect to see a 1Vp-p signal, offset from ground by ½ Vin.

The SPI should be at or close to the supply voltage for the chip (3.3V by default). If you elect to write your own SPI control for this, the clock idles low (CPOL = 0) and data are latched on the rising edge (CPHA = 1). This corresponds to SPI Mode 1.

MiniGen Signal Generator Board Resources

• MiniGen Schematic
• MiniGen Design Files for Eagle
• MiniGen Arduino Library with demo code and production files
• MiniGen Arduino Library Usage Guide
• Analog Devices AD8045 OpAmp Page with datasheet and other documentation
• Analog Devices AD9837 Waveform Generator Page with datasheet and other documentation