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What’s the I2C address configured by your PCF8574 module? Note that it has 3 bits that you can use to set the I2C address (if I understand correctly, these would be the 3 yellow-colored jumpers on your module). It’s not clear to me whether you are following OS 3.0, 3.1 or 3.2 schematic. Only 3.0 uses PCF8574 (whereas 3.1 and 3.2 use PCF9555 16-channel IO expander). So assuming you are following 3.0 schematic, which is available here:
https://github.com/OpenSprinkler/OpenSprinkler-Hardware/tree/master/OS/3.0/AC_driver
it assumes that on the AC driver board, the three bits are A0=1 (high), A1=A2=0 (low). You need to set the jumpers correctly to match this address.Hi, could someone help me with connecting PCF8574 to NodeMcu?
I compiled nad successfully uploaded a sketch to NodeMcu and all is fine except communication with PCFmodule – I set A0=1,A1=A2=0 and I can not change a state of SSR High level trigger… Should I change sth in source code?Hi, I bought PCF8574AP, connected it to NodeMcu with OLED display. Display works great but a module set High on all outputs and does not change after setting on in Openspringler. Could You help me?
I am not sure exactly which schematic you are following. As I said in my first reply: only version 3.0 board design uses PCF8574 — in fact, it uses one on the top level board, and one on the driver board. Revisions 3.1 and 3.2 do NOT use PCF8574, instead, they use a single PCA9555 IO expander chip. The reason is that PCA9555 is a 16-channel IO expander chip, while PCF8574 is 8-channel. So the original 3.0 design had to use 2x PCF8574, and later with PCA9555 it only needs one single IO expander chip. Also, PCA9555 uses totem output so can source much higher current into the traics on the driver board. PCA8574, on the other hand, uses weak pullup so cannot source high current (and for that reason OS 3.0 driver design had to use additional PNP transistors to provide high current).
Thank You for the response.
I’m following 3.0 version schemtaic
I found in my country PCA9555 so I’ll try use it 🙂If you follow OS 3.0 schematic, please note that there are two PCF8574 IO expanders, one on the top level (master controller), one on the bottom (AC-driver). The top level is set to I2C address 000, and bottom is 001. The bottom level controls solenoid drivers.
Hi, I bought PCA9555 ad everything works great but I have one question – is it possible to control 12 sections using one PCA9555?
By “12 sections” did you mean 12 zones? The main controller can only control 8 zones. If you want to go beyond 8 zones, that’s what the expanders are for: each expander uses one additional PCA9555 to add 16 zones.
The reason the main controller only does 8 zones is that among the 16 IO pins of PCA9555, 8 are used for zone control, the other 8 are reserved for other purposes: including button 3, boost converter control on DC-powered OpenSprinkler etc.
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