Connect STM32 to TTL IC (5V)

[pook_prinya]

Posted on January 09, 2009 at 12:20

Connect STM32 to TTL IC (5V)

[pook_prinya]

Posted on May 17, 2011 at 12:58

Hi,

Kindly advice how to connect STM32F103 to TTL IC which will accept 5V input, and with GPIO pin mode (PP or Floating) that I can use for output to TTL IC. I have tried to use TRISTATE BUFFER IC (SN74LCX245) for interfacing but it does not work. Thanks in advance Prinya

[jj]

Posted on May 17, 2011 at 12:58

Can you use a 74HC245 device - powered from 3V3? If you truly require level translation (3V3 to 5V) there are specialized devices dedicated to this task. Sorry can't recall family/part no. at this moment... (they do come in bus (8 bit) width as I recall)

[pook_prinya]

Posted on May 17, 2011 at 12:58

Hi,

Thanks for your advice. Kindly advices . What GPIO output pin mode (PP or Floating) should I use when I use this 74x245 family IC interface between STM32 and TTL (5V) IC? (or do I need also additional resistors). Thanks, Prinya

[pook_prinya]

Posted on May 17, 2011 at 12:58

Thank a lot. I will try tonight.

[lil-vince]

Posted on May 17, 2011 at 12:58

Hi,

Why don´t you use a five volts tolerant pin in output open drain with a pull-up on 5V? Or you can use: transistor, a xxxxxCTxx technology as your TTL IC or as interface. PS: Floating is a INPUT mode, output modes are open-drain or push-pull. Vince [ This message was edited by: lil-vince on 09-01-2009 09:06 ]

[cnicolls2]

Posted on May 17, 2011 at 12:58

You should be able to use 74AHCT245 running @ +5V. It's VIH = 2.0V, suitable for interfacing to the STM32's 3.3V output. You should configure the GPIO in push-pull mode.

Chris

[lil-vince]

Posted on May 17, 2011 at 12:58

This is what I wanted to say with:

Quote:

a xxxxxCTxx technology as your TTL IC or as interface. The ACT, HCT, AHCT, etc...(CMOS-TTL) technology have all a Vih of 2V with a supply of 5V. Vince [ This message was edited by: lil-vince on 09-01-2009 16:51 ]