shielded cable

[HTheatre]

Hi Georg,

Where did you connected the shields of the link between the 2 GRBL board ? It seems you connected the shield of TX to RX and the shield of RX to TX together, but I can't see where the brown wire (which seems to be connected to these shields) goes ?

See ya

[geostein8888]

Hello,
the brown cable is connected to the gnd of the grbl board, where also the 24V are coming in (lila and white cable)
i connected both sides of the shield together to the GND

georg

[geostein8888]

Hello,
i reprogrammed now the esp with the source linked here from mstrens, same result (no drivers/steppers still), at around 34% it stops and went to idle. in the message window i have some "oooo"

Georg

[mstrens]

The "oooo" confirms that there dummy characters received by the ESP32.
As those are not sent by the STM32 (GRBL) it means that there is something wrong with the connection between pin TX from grbl and pin RX from ESP32 (bad contact/soldering or noise). If the spindle and steppers are not under power I do not expect noise.
Check also if there is not a (bad) contact between the 2 pins TX and RX on STM32 (to much soldering or flux between adjacent pins?).

Make you Gnd wire (from shield) as short as possible and connect it closier (or directly) to the Gnd that goes to the ESP32 board.

[mstrens]

I also noticed that the character "o" is coded with all bits equal to 1 (level high) except 1 bit (at the beginning).
The normal level on the line is 1.
So probably that the line TX (GRBL) to RX(ESP32) is driven LOW from time to time for a short time (due to noise or a signal from an adjacent pin)

[geostein8888]

Hello,
to isolate this completely, i will now take the two boards completely out of the cnc and run them alone, while perhaps the power supply makes the problem i will use another one. While i have no circuit plans, does somebody know if i can use a 19V notebook power supply or even a 12V - normally this should be enough only for the gerbl, stm and esp to get the 5V

Georg

[mstrens]

As test, you can even make it easier.
Do not connect the Vcc wire between ESP32 and STM32 board. Keep the 3 other wires.
Connect ESP32 to PC with USB cable (it wil provide the power supply)
Connect STLInk to STM32 (it wil provide the power supply)
So you can now send the Gcode without any extra power supply.

This is the way I make tests.

[geostein8888]

Hello,
is the stm on the gerbl board for this test? i wanted to test all 3(4 - 2 red boards + stm + esp/tft) parts together.
and can i drive the gerbl port with less than the 24v,Reason is, when this works i will drive the board later also with a separate power supply

Georg

[mstrens]

Hello,
is the stm on the gerbl board for this test? i wanted to test all 3(4 - 2 red boards + stm + esp/tft) parts together.
and can i drive the gerbl port with less than the 24v,Reason is, when this works i will drive the board later also with a separate power supply

Georg

Yes you can let the stm32 on the grbl board for this test.
On the GRBL board there is a jumper that is normally installed. This jumper let the 5V (generated from the 24V) arrive to the STM32.

It is possible to remove the jumper and to provide the 5V from an external source. This was made for those who should whanted to connect directly the grbl board to the PC (without using the ESP32/TFT board) because it is not safe to provide 2 power supplies to the blue pill.
So, in principe you could let the 24V on the board but power up the STM32 from another way.
Still, this is not the final goal. The test we are making now is mainly to identify what is going wrong with your hardware. Once the reason identified, it should be possible to fix the issue and use the board in the way there are foreseen

[geostein8888]

Hello,
like planned, i took the complete electronic out of the cnc, connected the gerbl board to a 24V power supply (from an old network switch). Means i have only the gerbl + stm32 + esp board with tft running.
with this configuration, i still get the same problem with the "o" sign. i also shortened the gnd cable from the shield so its as short as possible

Georg