Bus Pirate Ultra prototype v1d: the last alpha

Bus Pirate “Ultra” v1d is stuffed and about half tested. This should be the last alpha “figuring out if we can pull this off” version. New in this revision:

Analog voltage measurement is now done from the FPGA using a 12bit 1 million samples per second ADS7042 Analog to Digital Converter. This will let us pipeline voltage measurement commands with other bus commands and reduce dependency on any specific MCU.

The programmable output power supply is now controlled by a DAC104S085CIMM Digital to Analog Converter chip, instead of the DAC in the MCU. This further reduces our dependency on a specific MCU, and will later allow us to control the voltage regulator from the command pipeline in the FPGA. It may be possible to simulate different power supply conditions and glitches, for example.

A lot more thought went into the programmable output power supply. V1d measures current through a shunt resistor, and we added a small load to test it. There’s several other goodies in there, but we’ll reveal them later.

In addition to sampling voltages on each IO pin from the FPGA, we’re now sampling several other voltages from around the board (power supply output, current consumption, etc) . We swapped the 8 channel 74HCT4051 analog multiplexer with a 74HCT4067 16 channel multiplexer. This part of the board needs some more thought because some of the voltages would be better measured without the divide by 2 resistor divider currently used after the op-amp.

The display daughter board now uses a 0.5mm pitch flex connector. We though these connectors and the flex cables would be a nightmare to work with, but they’re actually a lot of fun. They’re really compact too.

After a little more testing we’ll get to work on v1e, which should be the first beta and possibly the first version ready for a small production run. Find the latest updates and follow a group build of v1d in the forum.

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