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HIDman AXP


January 2025

The HIDman AXP is described on the GitHub web page at here.

I had PCBWay assemble/build a PCB for me (PCB + soldered-on components).  It arrived, and I went through the process of downloading the firmware (version 1.1.4) onto it.

Some notes of my experience follow.  In short, I can get the keyboard functionality in the HIDman AXP to work on my IBM 5150's, my IBM 5170, but not on an IBM 5160.  My experimentation with the IBM 5160 reveals that the AXP will work on the 5160 once the AXP's firmware (in XT mode) is enhanced to support the 'software reset' requests that most PC-class and XT-class motherboards make to the keyboard.

NOTE:  Do not confuse the HIDman AXP with other HIDman products.  E.g. HIDman PS/2.  E.g. HIDman mini.


Revisions

There have been some hardware changes.  At this time (DEC24), the PCB is at revision C.  ("HIDMAN AXP rev c" is printed on the PCB underside.)

Accordingly, there is a new 'front enclosure plate', one to cater for the LED now being directly under the switch (not as shown in the first photo at here).


PCBWay

The minimum PCB count is five, and so what I had to order was five PCB's, plus components for one PCB, plus assembly, plus postage.  (I did not balk at five PCB's, because $1 per PCB is cheap.)

Part way through assembly, I received an email from PCBWay containing photos, asking me to verify that the components were oriented correctly on the partially soldered PCB.  Upon receiving verification, they would proceed with assembly/build.

They also pointed out a discepancy about C1 and C12.  But that was of no concern because C1 and C12 are electrically the same, and being MLCC, have no polarity.

I found a decent photo online (this photo) of the HIDman AXP (revision 2), and used that to verify to PCBWay that all looked good.

On the assembled/built PCB that arrived from PCBWay, the soldering is very well done.  My PCB is green with white lettering, the default selections when ordering.

After receiving my assembled/built PCB, I needed to download the firmware onto it.

Later, I may look at getting the aluminium case and front+rear plates.  We will see.  The case (black or unpainted) can be purchased cheaper at multiple places.

Below, I will refer to my assembled/built PCB as 'unit'.


Discrepancies

•  On the BOM (bill of materials) at the GitHub site, resistor network RN3 is listed as 150 ohms.  PCBWay's BOM shows 120 ohms instead, and 120 ohms is what PCBWay fit.  RN3 is used to control the brightness of the the LED, and so the 120-versus-150 difference was not a concern to me.

•  As mentioned earlier, PCBWay pointed out a discrepancy about C1 and C12.  See here.  It was of no concern because C1 and C12 are electrically the same, and being MLCC, have no polarity.


Keyboard emulation: Switching between the three modes

After I downloaded the firmware (version 1.1.4) into my unit, I saw that the front panel LED turns on when the unit receives power.

At each momentary push of the 'keyboard mode' button, the unit cycles between three different keyboard emulation modes and the colour of the LED indicates the mode.  See this.

I notice that when the HIDman AXP gets powered, it 'remembers' the keyboard emulation mode that it was in when it got lost power.


Keyboard emulation: Trying with IBM 5150 (IBM PC)

Keyboard emulation mode is 'XT'  (AXP's front panel LED is orange).

Apart from the POST displaying a 301 error (keyboard not responding to soft reset request), the HIDman AXP (with 1.1.4 firmware) works for me.  This was for both the 16KB-64KB and 64KB-256KB type of IBM 5150 motherboard (both with 10/27/82 dated motherboard BIOS).

At the aforementioned GitHub web page, the "OG" in front of "OG IBM PC / XT and clones" is probably short for 'ongoing', and so there is probably a plan to stop the 301 error from happening.


Keyboard emulation: Trying with IBM 5160 (IBM XT)

Keyboard emulation mode is 'XT'  (AXP's front panel LED is orange).

On my IBM 5160's, the HIDman AXP (with 1.1.4 firmware) is not working for me.  Like for the IBM 5150, I see a 301 error, then some other stuff happens, then because of the error, I am prompted to press the F1 key.  The F1 key does nothing (apart from flickering the LED on the HIDman AXP).

That is for both the 64-256KB type of motherboard (with 08/16/82 dated motherboard BIOS) and 256-640KB type of motherboard (with 05/09/86 dated motherboard BIOS).

I pulled a couple of clone XT motherboards out of storage, and found that the HIDman AXP (with 1.1.4 firmware) works with those.  One of those displayed a keyboard error (similar to IBM's 301 error) at POST time, but after that, the keyboard worked.

See note 1 below for my investigation, and findings.


Keyboard emulation: Trying with IBM 5170 (IBM AT)

Keyboard emulation mode is 'AT'  (AXP's front panel LED is blue).

The keyboard emulation works for me.




Note 1 MY IBM 5160 INVESTIGATION:

- Putting in an ERSO BIOS mostly worked.  A keyboard error was displayed (".K-B Error !") but a boot to DOS happened, and at the DOS prompt, alphanumeric keys typed were presented on-screen.
- With the ERSO BIOS in, and reaching a DOS prompt, CHECKIT software shows the F1 key as working.
- The ERSO BIOS experiment showed that the problem is not related to the hardware on the IBM 5160's motherboard.
- I modified the 10JAN86 BIOS to skip asking for F1 to be pressed.  I got to a DOS prompt, but keyboard typing still did not result in characters appearing on-screen.
- I modified the 10JAN86 BIOS, this time, modifying the software reset code to fake a successful reset (i.e. pretending that the keyboard responded with AA to a software reset request). That worked; no 301 error, and keyboard typing worked.

SUMMARY:

IBM 5160 support is expected to be achieved when the HIDman AXP's firmware is enhanced to support the 'software reset' requests that most PC-class and XT-class motherboards make to the XT-class keyboard.
On the IBM 5150 and IBM 5160, that will also remove the annoying 301 error that the POST displays.
Until then, IBM 5160 support can be achieved by certain modification of the motherboard BIOS.

18JAN: Rasteri indicates that 'software reset' support is to be added to the XT mode, and the priority to do that will be raised.  Resolution aimed for in the next release of firmware, that is 1.1.5