The Rev-A board worked as expected, and needed. Although it fit and worked well, I thought of some nice tweaks and new functions, plus I wanted it to fit within a typical 1U rack-mount chassis envelope. Part of my master plan for a rack-mount, multi-output PSU!

The RPD (rev-B) specs and features include:

* VEXT = 9-24VDC main power input (for SMPS section).

* VBUS = 9-24VDC link-power for logic, which is supplied over the RS-485 control link. Can also be coupled to VEXT with a soldered-in wire, for standalone operation.

* Vout = 5-19VDC output voltage capability. I'm aiming for about 12A max output current at Vout=5V. TBD! Although the output can't go down to 0V, for driving DC motors I would normally use a fixed voltage and use PWM mode. A protective flyback-diode on the output terminals prevents destruction from inductive loads.

* Output voltage can be S/W controlled via serial-POT. Also, as a populate-option, you can make the output voltage fixed, or manually-adjusted using a standard trimmer-pot. You can't have all 3 methods in place at one time though. No more room for jumpers!

* Output stage can be S/W controlled: On/Off, PWM mode, also there's a braking-FET across the output terminals (sometimes handy for DC motors).

* 2 external GPIOs: Can be configured as a:

... Digital input, digital output

... A/D input

... 5V power out (to power external sensors or prox-switches).

... External on/off or PWM-input (controls the DC-output stage power switch).

... Drive a string of RGB-LEDs (WS2812B), and the high-current +5V would conveniently come from the main DC output terminals.

* 2 RJ45 connectors (optionally, 2 IDC 2x4 headers), which are for the RS-485 control link. There are link-termination jumpers as well. Also the RJ45's pin-6 /LINKIRQ signal is supported.

* 4 address jumpers - to set this board's "unit number" for the RS-485 control protocol. Therefore you can chain at least 16 of these modules on the same UTP cable.

* 4 status LEDs shining out the edge by the main terminal blocks: Vin, Vout, and 2 programmable indicators (generally used to echo show GPIO Sig1/Sig2 status).

* 256Kbyte (2Mbit) SPI-flash chip. Used for activity-logging, or to store pre-computed RGB-LED maps.

* PIC16F1829 is the microcontroller on this board.

* A/D measurement of Vext (9-24v main input), Vout (5-19V main output), and Iout (output current).

* Now nicely fits inside a 1U rack-mount equipment envelope. Height = 1.6". Mounts to a metal base-plate using right-angle screw-brackets (M3 or #4-40 threads).

What did I miss? I'm sure it can do something else.