I have been suffering for some time now to interface and ESP32-P4 with twai to a fault tolerant canbus system. The TJA1055/3 is on the breadboard and hooked up and I can measure the Rx output from the chip, which is supposed to be sent to an ESPGPIO, but seemingly this voltage output reaches about 3.2v for HI and only about 1.8v for LO, the ESP32 GPIO needs to see 0.8v for LO and so is not able to decode these pulses and read the received data. I have tried various sizes of pull up resistor on the Rx output of the TJA1055 but this makes very little difference and I have tried changing the termination resistors between pin 8 and 9 and the CAN H and CAN L signals, which also makes some difference, but not enough. Can anyone shed some light on how the get a usable signal from out the chip, or am I going to have to add additional signal conditioning between TJA1055 ans ESP GPIO
Hello donaldpitt
Good day!
You can reduce the value of Vol by reducing Iol, as shown below.
What current do you have at Iol?
If it's necessary to maintain the same current and it's not possible to lower it, I would recommend adding a MOSFET transistor to act as a buffer, choosing one that best suits your needs.
I hope this information has helped you, please let me know if you need help with anything else.
Have a great day and best of luck.
Thankyou for a valuable comment, I am going to try this in coming days and will report back, it is a bit complicated to get to testing this but I will . We have decided to use a Schmitt trigger to shape the output to suit, but if I can get the correct output for the ESP32 GPIO without adding another component, then i will embrace it with open arms. I am not an electronic engineer but an automation specialist, so while I do understand these things, I do not normally understand why and if the documentation doesn't spoonfeed, I get lost.