Spi Archive

MAX5214 Eval Board

I caught on to a promotion from AVNet last week, in which one may get a free MAX5214 eval board (available through August 31), so hopped on it because really, why wouldn’t I turn down free hardware? I promptly forgot about it until today, when a box arrived from AVNet.

What’s on the board

The board features four Maxim ICs:

  • MAX8510- small low-power LDO.  Not terribly interesting.
  • MAXQ622- 16-bit microcontroller with USB.  I didn’t even know Maxim make microcontrollers!
  • MAX5214- 14-bit SPI DAC. The most interesting part.
  • MAX6133- precision 3V LDO (provides supply for the DAC)
Board schematic
Board, front side
Board, back side

The MAXQ622 micro (U2) is connected to a USB mini-B port for data, and USB also supplies power for the 5V rail.  The MAX8510 (U4) supplies power for the microcontroller and also the MAX6133 (U3).  The microcontroller acts as a USB bridge to the MAX5214 DAC (U1), which it communicates with over SPI.  The SPI signals are also broken out to a 4-pin header (J6).


The software included with the board is fairly straightforward, providing a small variety of waveforms that can be generated. It’s best demonstrated photographically, as below. Those familiar with National Instruments’ LabView environment will probably recognize that this interface is actually just a LabView VI (Virtual Instrument).

Waveform generator GUI


Rather more interesting than the stock software is the possibility of reprogramming the microcontroller. Looking at the board photos, we can see that there’s a header that breaks out the JTAG signals. With the right tools, it shouldn’t be very difficult to write a custom firmware to open up a communication protocol to the device (perhaps change its device class to a USB CDC for easier interfacing). Reprogramming the device requires some sort of JTAG adapter, but I can probably make a Bus Pirate do the job.

With some custom software, this could become a handy little function generator- its precision is good and it has a handy USB connection. On the downside, the slew rate on the DAC is not anything special (0.5V/µs, -3dB bandwidth is 100 kHz), and its output current rating is pretty pathetic (5 mA typical). With a unity-gain amplifier on the output though, it could easily drive decent loads and act as a handy low-cost waveform generator. Let’s get hacking?