BOB-09056 incorrect documentation?

Other Miscellaneous
1

Hi, I’m new here… :slight_smile:

I just picked up a 16 channel multiplexer breakout: https://www.sparkfun.com/products/9056

After getting it all wired up, it seems that the documentation is wrong for which s0-s3 high/low signals control which output connection

https://www.sparkfun.com/datasheets/IC/cd74hc4067.pdf

I’m using a 4-channel 3v-5v step up(74acht125), between the multiplexer and a raspberry pi, which doesn’t have enough outputs for me to use s3 on the multiplexer (en, s0, s1, s2), meaning that s3 is always “low”, which should mean that I can’t use s8-s15. (requires s3 to be “high”)

high/low combinations for c0-c3 seem to be correct, but c4-c8 actually control c12-c15

Am I reading the documentation wrong?

2

This may be a stupid question, but did you actually connect s3 to ground or did you leave it floating?

3

I didn’t ground it, noob mistake? I’ll try that out, thanks!

4

Digital inputs must be tied to either high or low, as appropriate. If you leave them floating, they will be in an unpredictable state. Here are some references:

https://learn.sparkfun.com/tutorials/logic-levels/all

https://learn.adafruit.com/circuit-play … ing-inputs