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#21
A20 / Re: HDMI connection back feedi...
Last post by LubOlimex - March 03, 2026, 04:50:23 PMIt will probably not lead to hardware failure but it is not very good, some hardware might be left at dubious levels when you power it for real.
Maybe it can be improved from the settings of the HDMI device like disable CEC mode or disable power link, for example.
You can also test with another HDMI equipment or first power the board before powering or attaching the HDMI device.
What is the monitor exactly?
Maybe it can be improved from the settings of the HDMI device like disable CEC mode or disable power link, for example.
You can also test with another HDMI equipment or first power the board before powering or attaching the HDMI device.
What is the monitor exactly?
#22
A20 / HDMI connection back feeding i...
Last post by dry - March 03, 2026, 02:30:05 PMI noticed that red power led is on on A20-CAN board which I plugged into the GPIO3 on the A20 micro board, even though power was not connected.
After disconnecting all but HDMI, then removing it, i saw red led going off. I measure about 1.8V on VDD1 tp and 1V on VREF test points on that CAN extension board, and I measure bout 1.8V on the 5V pin on GPIO 1 connector on A20 micro board.
So is this back-feeding a problem for overall usage, will I get any weird gremlins?
(Perhaps unrelated, but I noticed that ethernet may not be found on some boots..)
After disconnecting all but HDMI, then removing it, i saw red led going off. I measure about 1.8V on VDD1 tp and 1V on VREF test points on that CAN extension board, and I measure bout 1.8V on the 5V pin on GPIO 1 connector on A20 micro board.
So is this back-feeding a problem for overall usage, will I get any weird gremlins?
(Perhaps unrelated, but I noticed that ethernet may not be found on some boots..)
#23
ESP32 / Re: New ESP32-POE-ISO - was I ...
Last post by LubOlimex - March 03, 2026, 09:21:41 AMUmm, you have to measure between pin 1 and pin 3 (GND and VIN). Write down the measurement that goes in. It should be around 4.6V.
Then measure between pin pin 1 and pin 2 (GND and SW). Write down the measurement that goes out. It should be 3.10V-3.20V.
Instead of using pin 1 for GND, for easier time measuring you can use any other GND, for example the pad of EXT1 header.
It is a bit tricky since U7 is small and pin 2 and pin 3 are next to each other at the side of the EXT1 header but I did it today so it is doable.
Then measure between pin pin 1 and pin 2 (GND and SW). Write down the measurement that goes out. It should be 3.10V-3.20V.
Instead of using pin 1 for GND, for easier time measuring you can use any other GND, for example the pad of EXT1 header.
It is a bit tricky since U7 is small and pin 2 and pin 3 are next to each other at the side of the EXT1 header but I did it today so it is doable.
#24
PIC / Re: PIC-USB-4550 program does ...
Last post by LubOlimex - March 02, 2026, 04:48:39 PMUmm wrong compiler for that code. You need PIC18 compiler in LITE mode:
https://www.microchip.com/en-us/development-tool/sw006011
It is free to download just requires registration.
https://www.microchip.com/en-us/development-tool/sw006011
It is free to download just requires registration.
#25
PIC / Re: PIC-USB-4550 program does ...
Last post by emil_bbb - March 01, 2026, 10:37:42 PMI have also tried to compile the program in MPLAB X IDE v6.25 but I get error messages.
make -f nbproject/Makefile-default.mk SUBPROJECTS= .build-conf
make -f nbproject/Makefile-default.mk dist/default/production/Bootloader.X.a
make[2]: Entering directory 'C:/Users/Emil.BC/MPLABXProjects/Bootloader.X'
"C:\Program Files\Microchip\xc8\v3.10\bin\xc8-cc.exe" -mcpu=18F4550 -c -mdfp="C:/Program Files/Microchip/MPLABX/v6.25/packs/Microchip/PIC18Fxxxx_DFP/1.7.171/xc8" -memi=wordwrite -O0 -fasmfile -maddrqual=ignore -xassembler-with-cpp -mwarn=-3 -Wa,-a -DXPRJ_default=default -msummary=-psect,-class,+mem,-hex,-file -ginhx32 -Wl,--data-init -mno-keep-startup -mno-download -mno-default-config-bits -std=c99 -gdwarf-3 -mstack=compiled:auto:auto:auto -o build/default/production/bootloader.p1 bootloader.c
In file included from bootloader.c:6:
C:/Program Files/Microchip/MPLABX/v6.25/packs/Microchip/PIC18Fxxxx_DFP/1.7.171/xc8\pic\include\proc/pic18f4550.h:41:2: warning: Header file pic18f4550.h included directly. Use #include <xc.h> instead. [-W#warnings]
41 | #warning Header file pic18f4550.h included directly. Use #include <xc.h> instead.
| ^
bootloader.c:22:5: error: use of undeclared identifier '_asm'
22 | _asm goto _startup _endasm
| ^
1 warning and 1 error generated.
make[2]: Leaving directory 'C:/Users/Emil.BC/MPLABXProjects/Bootloader.X'
make[2]: *** [nbproject/Makefile-default.mk:104: build/default/production/bootloader.p1] Error 1
make[1]: *** [nbproject/Makefile-default.mk:85: .build-conf] Error 2
make: *** [nbproject/Makefile-impl.mk:39: .build-impl] Error 2
BUILD FAILED (exit value 2, total time: 1s)
I find it impossible to load a working programm in the pic
Is there any other programm that works with the bootloader, other than the blinking led?
make -f nbproject/Makefile-default.mk SUBPROJECTS= .build-conf
make -f nbproject/Makefile-default.mk dist/default/production/Bootloader.X.a
make[2]: Entering directory 'C:/Users/Emil.BC/MPLABXProjects/Bootloader.X'
"C:\Program Files\Microchip\xc8\v3.10\bin\xc8-cc.exe" -mcpu=18F4550 -c -mdfp="C:/Program Files/Microchip/MPLABX/v6.25/packs/Microchip/PIC18Fxxxx_DFP/1.7.171/xc8" -memi=wordwrite -O0 -fasmfile -maddrqual=ignore -xassembler-with-cpp -mwarn=-3 -Wa,-a -DXPRJ_default=default -msummary=-psect,-class,+mem,-hex,-file -ginhx32 -Wl,--data-init -mno-keep-startup -mno-download -mno-default-config-bits -std=c99 -gdwarf-3 -mstack=compiled:auto:auto:auto -o build/default/production/bootloader.p1 bootloader.c
In file included from bootloader.c:6:
C:/Program Files/Microchip/MPLABX/v6.25/packs/Microchip/PIC18Fxxxx_DFP/1.7.171/xc8\pic\include\proc/pic18f4550.h:41:2: warning: Header file pic18f4550.h included directly. Use #include <xc.h> instead. [-W#warnings]
41 | #warning Header file pic18f4550.h included directly. Use #include <xc.h> instead.
| ^
bootloader.c:22:5: error: use of undeclared identifier '_asm'
22 | _asm goto _startup _endasm
| ^
1 warning and 1 error generated.
make[2]: Leaving directory 'C:/Users/Emil.BC/MPLABXProjects/Bootloader.X'
make[2]: *** [nbproject/Makefile-default.mk:104: build/default/production/bootloader.p1] Error 1
make[1]: *** [nbproject/Makefile-default.mk:85: .build-conf] Error 2
make: *** [nbproject/Makefile-impl.mk:39: .build-impl] Error 2
BUILD FAILED (exit value 2, total time: 1s)
I find it impossible to load a working programm in the pic
Is there any other programm that works with the bootloader, other than the blinking led?
#26
ESP32 / Re: New ESP32-POE-ISO - was I ...
Last post by chrismacp - March 01, 2026, 12:29:42 AMI'm wondering, before I start trying to solder anything. Are there any measurements I could take to confirm where the problem is. I'm most definitely an amateur at this stuff currently so trying to learn where I can.
I measured ~1.9v across pin 1 (GND) and pin 6 (Out according to datasheet although just 'x' in the Kicad file) of U7 when there is 5v applied to the 5v pin of the microcontroller board. It's ~1.4v when usb power is connected.
I'm not sure if that helps to figure out if the component is broken or not.
I measured ~1.9v across pin 1 (GND) and pin 6 (Out according to datasheet although just 'x' in the Kicad file) of U7 when there is 5v applied to the 5v pin of the microcontroller board. It's ~1.4v when usb power is connected.
I'm not sure if that helps to figure out if the component is broken or not.
#27
ST / Re: BB-STM32WL and Platformio/...
Last post by LubOlimex - February 27, 2026, 08:41:49 AMI think you are correct. It seems the ESP-PROG design was made only for ESP boot sequence. I will add it as a note on the product page. Maybe jut use regular general-purpose USB-serial cable. Like:
https://www.olimex.com/Products/USB-Modules/Interfaces/USB-SERIAL-L/
USB-SERIAL-L does not internally couple RTS and CTS. But you must wire it properly and probably put like 1k resistor between RTS and boards RESET and between CTS and BOOT0.
https://www.olimex.com/Products/USB-Modules/Interfaces/USB-SERIAL-L/
USB-SERIAL-L does not internally couple RTS and CTS. But you must wire it properly and probably put like 1k resistor between RTS and boards RESET and between CTS and BOOT0.
#28
ESP32 / Re: What board should I use?
Last post by LubOlimex - February 27, 2026, 08:22:57 AMOf course, PoE is optional. You can still power them from USB or external power supply and have a back-up Li-Po battery. The Ethernet is fully functional as long as the board is powered.
Notice that you can stack more than one MOD-IO board, just change the I2C address of the second, the third, and so on.
Notice that you can stack more than one MOD-IO board, just change the I2C address of the second, the third, and so on.
#29
ST / Re: BB-STM32WL and Platformio/...
Last post by winfried - February 26, 2026, 04:42:05 PMWorkin manual: the sequence is with buttons to GND:
BOOT0 -> low (button closed)
RESET -> low (button closed)
RESET -> high (button released)
BOOT0 -> high (button released)
--
To understand the Transistor Logic in ESP-PROG it did, thanks to KiCAD, a fast simulation on /RTS and /DTR to DCOM and EN see picture below:
It seems, there is no combination of both signals being low at the same time, so it does not work, or am I wrong ?
BOOT0 -> low (button closed)
RESET -> low (button closed)
RESET -> high (button released)
BOOT0 -> high (button released)
--
To understand the Transistor Logic in ESP-PROG it did, thanks to KiCAD, a fast simulation on /RTS and /DTR to DCOM and EN see picture below:
It seems, there is no combination of both signals being low at the same time, so it does not work, or am I wrong ?
#30
ESP32 / Re: What board should I use?
Last post by fredy - February 26, 2026, 02:58:02 PMHi!!
Thanks for response and your advise!
Last question: could I use POE boards without use the power of POE and use the ethernet to send data?
Thanks in advance!
Thanks for response and your advise!
Last question: could I use POE boards without use the power of POE and use the ethernet to send data?
Thanks in advance!