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Hi to all!
My doubt is about connections between E220 modules and arduino (UNO, NANO)
In E220-900T-22D datasheet I saw a image with connections between an generic microcontroller and E220 module. In the image all connections are direct without pullups nor voltage dividers.
And in Mischianti connections diagram between E220 modules and arduino UNO, exist pullup and voltage divider on RX pin from the module.
Well, in Mischianti text he recommend to use pullup in all connections to avoid freeze the module. And the recommendation is understandable.
However, I could not understand the need for the voltage divider, since according to the datasheet it is clearly stating that both signals (TX/RX) are TTL, which is understood to be 5V tolerant.
Is there any information I missed in the texts?
Thanks
Ivan Assaritti
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Hi Renzo.
I’m sorry, you’re right, but I saw only this line with this specification:
“Communication interface UART Serial Port TTL Level”
Well, all my tech life, I suposed “TTL Level” was 5 Volts, not 3.3 Volts.
I should have paid more attention to all the information in the datasheet.
With this information I have another doubt:
If RX work with only 3.3V, I supose the TX pin from E220 have 3.3V level in it. You see problem to arduino receive data in RX pin with this level or could be better to use a voltage level module complete for TX/RX?
Thanks,
Ivan
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