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Level shifter with mcp2515 module

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dhakeparag81

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Hello,

Can i interface txs0108e with mcp2515 module?
I am using pic32mm0256gpm064 controller which is 3.3v, and mcp2515 module is 5v, i have tried the module on 3.3v its working but when i checked the tx and rx count in mcp module it increased means i have lost some of the packages.
I think its due to TJA1050, because its datasheet says this device is compatible with 3.3v devices but its power is 4.75 min to 5.25 max.
Any suggestions?
 

Hi,

you get more and better response when you post links to the datasheets.
A simple sketch or a schematic is also a good idea to motivite members to reply.

Klaus
 
I'm attaching some datasheet links below,
I forgot to mention that in currently power the mcp2515 module with 3.3v.
TXS0108E level shifter datasheet
Mcp2515 datasheet
TJA1050 datasheet


There, those link should work.
This schematic is the standerd diagram for mcp2515 can bus module downloaded from internet.
I mentioned the pic part number just to give the idea that iam using this part.
TXS0108e is the ic I found for level shifting and I'm planning to use that, ADUM1401 is the best option for isolation regarding 3.3v controller side and 5v on mcp2515 module side but this is so expensive.
For the VCC as I'm currently powering up the mcp2515 module with 3.3v as my controller works on 3.3v, also mcp2515 ic is ok for this voltage but TJA1050 power supply is different as I mentioned 4.75 to 5.25v.
Iam planning to give 3.3v on port A (vcca) and 5v on port B (VCC) of TXS0108e, but this ic is 8channel bidirectional and u have never used it. So may be someone is tried before this ic with spi port.
 

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Hi,

The links don´t work .. at least for me.
Did you use the [insert >Link] button?

It´s a bit confusing.
Your question is this:
Can i interface txs0108e with mcp2515 module?
But you also talk about PICxx --> I guess it´s not involved in the problem at all.
Your schematic does not show txs0108e at all --> how is your idea about it´s connections? signals and supply?
(please show a schematic that exactly shows your problem, so we all can exactly refer to each device and signal)
We don´t know what voltage "VCC" in your schematic means.

I guess the problem is just related to the signals RxD and TxD between MCPxxx and TJAxxx. Is this correct?

Klaus
 

Hi,

the level shifters from TI are working fine, I used the TXB010x serveral times. There is also a two bit version available [1]. You already noticed that side A has to be powered with, the lower voltage, below 3.6 V. There is no direction control needed.

The TJA1050 dataseheet mentions “Input levels compatible with 3.3 V and 5 V devices“, so if you can use a 5 V tolerant input pin of your mcu (if available at all), you might not need a level shifter.

[1]https://www.ti.com/product/TXB0102

BR
--- Updated ---

... I got somehow confused by the mentioned MCU, I haven't checked the DS and though it supports CAN. So to connect the TJA1050 and the mcp2515, a level shifter is needed, as the absolut maximum input voltage of the mcp2515 is VDD + 1V.
 
Last edited:

Hi,

You talk about a module.
* If it´s just the IC, then please don´t call it module.
* If you have a module, then give a link to the module_datasheet, beause it may have additional circuitry.

I agree that the TXS0108 will work properly. They do what they should do.

I´m still not sure about your exact (problematic) configuration and exact problem.
Is the situation of the question:
* mcp2515 @3.3V <--> TJA1050 @5.0V
If so:
* 3.3V mcp2515 signal output ---> 5.0V TJA1050 signal input (no level shifter needed)
* 5.0V TJA1050 signal output --->resistive voltage divider ---> 3.3V mcp2515 signal input

Klaus
 

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