Hi,
I am working on a shield for the Arduino Due that's supposed to read from mulltiple flow and pressure sensors (2 devices operate at 3v3 and one at 5v , different addresses). The sda and scl lines of all devices are connected via pull-up resistors to 3v3 to the SDA1 and SCL1. I tried substituting the Wire commands to Wire1.xxxx however the sensors aren't detected.
I've included a picture of the eagle schematic.
Any help is much appreciated!
Edit: I've noticed that sensor 3 bypasses the pull-up and is directly connected to SDA1 and SCL1, can that also have an effect on sensor 1 and 2 as they are still not being detected by the arduino?
A tiny, almost unreadable picture.
Bypasses it where? On the shield or on the Due board? It's not possible to bypass the pullup resistors on the Due board.
Noticed? How can you notice something that you designed yourself? Puzzled.
It bypasses the pullup resistors on the shield, no the shield wasn’t designed by me
How can the resistors be bypassed anywhere at all? They are not wired in series. Are you saying there are separate pins or jumpers for the pull ups, such that you can connect/disconnect them from the I2C lines?
Well
this usually means you are the designer. Sensor 3 is the 5v sensor?
There are three i2c sensors
Sensor 1 operates at 5v and sensor 2 and 3 both operate at 3v3.
Now i was handed the shield above and my task is to find why the sensors aren’t reading anything.
I noticed that both sensor 1 and sensor 2 sda and scl are connected to 4.7 kiloohms pullup resistors to 3v3 and then to sda1 and scl1.
For some reason however sensor 3 sda and scl pins are connected directly to the same sda1 and scl1 without pull-ups (i would’ve added them in series to the other sensors and used two pull-ups one for sda and one for scl)
My question is if that might be the problem as sensor three causes the potential on sda1 and scl1 to float?
With no schematics or documentation? Verbal descriptions don't cut it. If you were provided those, please post them, along with a wiring diagram showing the sensor connections. If it's based on your own reverse engineering, please make diagrams and post those.
RLB8721.pdf (404.7 KB)
I've uploaded a (hopefully) better quality of the shield and highlighted the path where i suspect that something is wrong.
Not useful at all. It is too much to expect of forum helpers, to translate a printed and hand annotated PCB layout to a schematic or an understanding of how things are connected. Please do that for us. Thanks in advance.
Regards your question, do you understand that all the pull up resistors on a given I2C bus, are effectively in parallel, and thus common to all the devices on the bus?