Is there a simple module with 5v/3.3V level shift AND step down?

Projects General Guidance
1

It just seems to be messy to have to design and implement both a separate 3.3V power section and one/two level shifters just because you use, for example an ESP-05 WiFi module.

It can't be that hard to put both on one small adapter board so that the 3.3V module can simply be attached to the adapter which attaches directly to a 328 bareboard/clone.

Does anyone know of an adapter with four inputs (5V, ground, TX, RX) and four outputs (3.3V, ground, TX, RX)? Under the right speed conditions the same module may be capable of I2C instead of serial.

If there isn't an existing module, does anyone have a relatively simple schematic, preferably using parts that an old man can solder?

I'd really appreciate a nudge in the right direction.

2

There are level shifters having what You ask for, a 5 volt pwr and logic side and a 3.3 volt logic side.

1 Like
3

I figured it was simply too easy and logical and therefore there had to be one/some out there. I just haven't been able to find one. Can you name one? My best friend Google hasn't found any yet...

4

https://www.sparkfun.com/products/12009 Its been around for years.

I use the $2 eBay 3.3V pro minis for 3.3V devices and avoid all those hassles entirely. Never had one fail yet.

5

I entered the words "level shifter" into a search engine and got a whole load of results.

6

And these work quite well

as bi directional level shifters.

7

JaBa:
I figured it was simply too easy and logical and therefore there had to be one/some out there. I just haven't been able to find one. Can you name one? My best friend Google hasn't found any yet...

I have bought such devices from Ebay but that order does not display any more. Go to Ebay and search for logic shifter, voltage shifter, etrc.

8

Level shifters like that don't work that well (or at all) for TX/RX, only for I2C.
Just use a 2-resistor 1k:2k2 voltage divider on the RX pin of the module,
and a Schottky clamping diode (1N5819) from the TX pin to 3.3volt (cathode/ring to 3.3volt).
Assuming you use SoftwareSerial on an Uno, or a hardware serial port on a Mega.

Big board Arduinos (Uno/Mega) can power these boards (~80mA) from their 3.3volt pin (~150mA), if... you support the 3.3volt power rail with a ~470uF cap (to bridge the short ~400mA transmit spikes).
Leo..

9

The OP seems to be looking for something like these:

eBay!
This is a two channel I2C level shifter with an on-board 3.3 V regulator as the OP describes. They are however, becoming rarer over time as the regulator function is not often wanted.

I have used them with the RC522 modules for the down-shift interface; not needed to convert 3.3 V up to 5 V as the Arduino will accept the 3.3 V levels OK.

That said, these are really only for bi-directional shifting on I2C as the same level conversion down to 3.3. V can be performed with a single diode and possibly a pull-up - as in the Adafruit Huzzah.

10

Circuit in post #5 is what I've done.