I want to program my PIC18F452 from long distances using a SIM808. by searching in the net I found out that I should follow this procedure:

I should write two different programs in the micro: a bootloader program and the main program.

The bootloader program checks the latest version and if it is the same, it enters the main program or otherwise deletes the original program and launches the new program.

I also need a site to put the binary file of my program there and the binary file will be downloaded exactly when the site opens, and then I should open the link with the sim808 and drop the binary file instead of the original program that was deleted.

For the bootloader, I'm using the application and the tutorial in the below link.

Now my problem is:

  1. I can write the bootloader hex file on the micro but the bootloader PC application doesn't recognize the COM ports when I connect the PIC using CP2102 USB to TTL module. What should I do? Are there some drivers I need to install for this?
  2. Is the procedure that I emphasized correct?


  • \$\begingroup\$ So what exactly is the problem; (1) PC does not recognize the USB device at all, (2) PC recognizes USB device just fine, but program can't see/open it, (3) PC recognizes USB device, program sees/opens it, but can't communicate with the bootloader? \$\endgroup\$
    – Justme
    Jan 12, 2022 at 7:48
  • \$\begingroup\$ pc does recognise the cp2102 module and i can send and receive a text with hterm but the bootloader program which is true track bootloader can't see or open com ports \$\endgroup\$
    – salar1991
    Jan 12, 2022 at 9:08
  • \$\begingroup\$ So what is the COM number then? If the program supports opening only COM ports 1 to 4, you can't open ports COM5 to COM255 with it. \$\endgroup\$
    – Justme
    Jan 12, 2022 at 9:22
  • \$\begingroup\$ hterm shows com15 when I connect the cp2102 module are there any other bootloader programs that can support com15 for example? \$\endgroup\$
    – salar1991
    Jan 12, 2022 at 9:54

1 Answer 1


The USB device is COM15 and the program can only open COM1 through COM4.

Change the USB device name to something that the program can open.

  • \$\begingroup\$ thanks changing the name did work and now the bootloader recognizes the open com port but now when I want to program the board it says connection not acknowledged. what is the problem ? \$\endgroup\$
    – salar1991
    Jan 12, 2022 at 10:43
  • \$\begingroup\$ Since the original problem is answered and solved, and you have a new different problem, it might be best to start a new question about it instead of continuing endlessy with new questions here. \$\endgroup\$
    – Justme
    Jan 12, 2022 at 10:48
  • \$\begingroup\$ that right thanks for your help \$\endgroup\$
    – salar1991
    Jan 12, 2022 at 10:52

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