Request: USB HID Test code for 18LF14K50 12MHz [Solved]

temtronic · Posted: Sat Oct 23, 2021 5:35 am

I thought CCS supplied an example, maybe in newer versions of the compilers ?

dyeatman · Joined: 06 Sep 2003 Posts: 1946 Location: Norman, OK

Yes. In my latest version compiler I have a total of 42 USB related driver and
example files but, as you know, we are not allowed to post them or give them
to anyone. The OP will have to request them from CCS.
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temtronic · Posted: Sat Oct 23, 2021 7:14 am

wow ! 42 USB examples !! That's more than the TOTAL number of examples from the 1st version of CCS I bought !!

providing the OP has registered his compiler, CCS will probably send him the 'examples' folder. They did that for me. I asked ,just to see how they 'cut code', to save me time reinventing the wheel .

Ttelmah · Joined: 11 Mar 2010 Posts: 19658

Yes, and the CDC example will work with the LF. All you have to do is change
the header to be for the LF instead of the F, and it runs. The E3 board header
works with the LF chip (I've used it).

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

Ttelmah · Joined: 11 Mar 2010 Posts: 19658

PCM, I used a board with the same layout as the E3 board, except with a
3.3v supply to the chip. Using compiler 5.101, and just copied the
usb common file to use the LF where the F was used for this board.
5.101 was the latest compiler when I did this, and it ran file with
ex_usb_serial.
So if your board is compatible with the E3, this is where I would start.

Best wishes.

FFT · Joined: 07 Jul 2010 Posts: 92

Hello guys,

I will give you more details;

* Here is my schematic (simplified - usb+pwr only) https://ibb.co/Fn762XN
VBUS pin is connected to 3.3V VCC externally, but I see 3.1V when I cut the connection. I tested both. It seems VBUS is connected to VCC internally too.

* I use CCS v5.104

* I have 12 Mhz NX5032 crystal with 22pF caps

I have shared a test code before, here is the latest code derived from mouse example (please remove if it's not allowed)
I tested several delay configs and fuses but there is absolutely no action when usb is plugged in. PIC's USB plays dead!

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

I made it work right now. I used an 18F14K50 (not LF) running
at +5v. I made a project for Ex_usb_serial.c in MPLAB vs. 8.92.
I used CCS vs. 5.103 simply because it was already installed.
I created the project in the CCS Examples folder, and named the
project "Ex_usb_serial". I added Ex_usb_serial.c to the project.

In Ex_usb_common.h, I commented out this line:

Ttelmah · Joined: 11 Mar 2010 Posts: 19658

When you say that you cut the Vusb connection, are you still leaving D+
and D- connected to the USB bus?. If so, what happens then is that the
transceivers get reverse biased, and power is fed through them into the
Vusb pin. I've known people successfully run the USB, without Vusb
connected (though with terrible reliability), because this happens....

There is a possible issue with the resistor values used on your detection
of the usb power connection. You have 10K+15K, so a voltage divider
giving 3v out from 5v. Usb V+, is only warranted to be 4.4v minimum.
The pin you are using for the Vbus detection has a schmitt input, so the
signal needs to get to above 2.64v. If the supply voltage on your USB bus
is at the lower end of the scale, and there is any resistance drop in the
plug, the chip won't be detecting that the bus is powered....
I'd suggest dropping the upper resistor to 8.2k. This might be causing an
issue.

FFT · Joined: 07 Jul 2010 Posts: 92

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

The hex file shown below was created with CCS vs. 5.105.
I tested it with both Windows 10 and XP and it enumerates.
I think it should also work with the LF PIC. Here are the fuses:

FFT · Joined: 07 Jul 2010 Posts: 92

Thank you. I just tested it on LF chip and it didn't work as before. I will test the code on F chip tomorrow.

Here I'm sending you my hex code for LF chip, fuses are the same like yours.

Could you please (if suitable) test it on your F chip?
It's the same usb serial code generated by your explanations above, just for LF chip.

Thanks.

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

Yes, your hex file works on my F part. It enumerates.

FFT · Joined: 07 Jul 2010 Posts: 92

I tested it with an F chip and it works.

Then I replaced the LF chip with a new one, I programmed it carefully at 3V using pickit3 over mplab once again and It showed a sign of life that enumeration started at Windows 7 but could not find driver.
Later I tested it on linux and it came as ttyACM0 usb2serial device.
Finally I installed the driver in CCS folder and it looks OK.

(I think I burned the other LF chips' USB somehow)

When testing the firmware;
- Docklight cannot see it's com port.
- TeraTerm sees it but when I press '!' it didn't send any HELLO messages as in the code.
- Hercules sees it but the same with the '!' key and echo character.

What am I missing?

PCM programmer · Joined: 06 Sep 2003 Posts: 21708