!!! A NEW, more advanced repo, (based on this one) is: here:

• It can handle +2 chip types: MCP23008 and PCF8575.
• It has better configuration possibilities via Node-red GUI. (eg. I2C addr A0 A1 A2)
• Auto limiting the MCPxxx chip's output problems on 7. + 15. pins.
• Has a "Legacy" checkbox to use this node's behaviour for backward compatibility.
• Working IRQ! (Tested.)
  ... see full list of change logs of his excellent work.

This is a Node-Red node for the MCP23017 & PCF8574 chips

• About Node-Red link...
• Link for the MCP chip itself
• Chip specs. PDF
• Link for the PCF chip itself
• Chip specs. PDF
• Node-RED node
• Github source
• NR. Forum discussion

Code Language:

• Node.js
• JavaScript
• HTML

About

It uses the config node "mcp_pcf_chip" for all reading and writing on i2c bus
More about I2C...

• Each pin (8 or 16 in total) can be individually selected to be an input or output
• You can place as many Nodes to your flows as many pins you use, or
• you can also set 1-1 node only pro 0-7 or 8-15 and control via msg.pin and msg.state if msg.payload=-1
• 4 states are showed of a node: On=green Off=grey Uninitialised=yellow Error=red

Requires 'i2c-bus' module. link...
( It gets automatically installed, except if you want to use it directly from function nodes. )

Inputs

WARNING: input interrupts part of this component is experimental.

• it reads inputs non-stop, can be set milisec value (a bit higher CPU usage)
• it might starts multiple timers that interfere with each other? (Needs investigation.)
• to minimize state-refresh problem there is secondary "de-bounce" timer

Config

• Each node has a global Main-Chip, that can be configured with "I2C bus number" + "Chip Address". (The PCF8574(A) chips are showed currently with an Address multiplied by 2. Like: 0x21 * 2 = 0x42 )

• Interval: is used to determine how frequently all inputs are polled. ( Reads all 8+8 ports from bank A+B. )
  ! Should be minimum 20ms, because a read process of 16 pins takes 12-14ms on a Raspberry Pi 4.

• Bit: is a number from 0 to 15 reflecting the pin (0-7 at FCP8574 chips) If "All0" or "All1" is recieved, the bit becames: -1 in logs.

• Pull Up: engages the low power pull up resistor. More: https://en.wikipedia.org/wiki/Pull-up_resistor
  (Inputs only.)

• Debounce: is a timer where the state must remain at the new level for the specified time (millisec)
  (Inputs only.)
  ( It will filter out too short changes, like sparkles. )

• Invert is a software-override for both Input + Output pins. It will show and act the opposite way of On/Off.
  0>>1 , 1>>0
  ( For example some relay boards are "closing = pulling" if they get GND instead of 5V on their pins,
  so they need to be negated with resistors. In those cases the chip must get 0x00 to "turn on". )

• Start All Outputs High: when node-red is started and first chip gets inicialized, it will send a 0xFFFF signal to all pins, so they

Known problems:

1. After disconnected of cable or USB-I2C adapter the readouts can not properly restore unless restarting the whole flow.
2. Multiple Main-chip-setup-nodes can be set to same Address, causing conflicts. (No pre-error or pre-warning happens.)
3. -- fixed 2022-03-26
4. It changes the On-Off state visually of the Node while it's not that node changed when using direct-msg-control
5. Sending "All0" or "All1" to an MCP node turns on only 0-7 pins, if Bit of Nodes are only set to 0-7. Solution: Set Bit of the node at setup to 8-15 to turn ALL!

To Do

1. Don't even allow already selected bits to be selected again (not just error reporting about)
2. When a node is deleted or disabled - remove from ids (array in chip) --- half done at 2022-03-19 version
3. Block RW operations happening at the same time... (rework everything to Async / await and atomic flags)
4. Analize further how interrupts are dealt with in C code and write it in s/mcp23017)
5. Don't allow to create multiple main chips with the same address (MCP + PCF can be on the same address accidentally)

Credit

Thanks to Mike Wilson for the original v0.1 node: MCP23017chip

Change Log 2022-09-09 (Y-M-D) Version: 2.4.0.20220909

by László Szakmári (www.pizzaprogram.hu)

• Better Logging options at chip node: log2consol : default True ; (If changed to False, it will not put log messages to node-red-log) logTimer : default False; (If changed to True, it will create lot's of interrupt and timed-red logs!) Max lines of logs are set to 1000 lines. (After that no more logs are added, so it will not overfill Node-RED's log system.)_ It can be changed by editing the: var logMaxLines = 1000; inside mcp-pcf-aio.js file at 50. line. Added require("worker_threads") dependency;

Change Log 2022-09-08 (Y-M-D) Version: 2.3.9.20220908

by László Szakmári (www.pizzaprogram.hu)

• Changed INTerrupt CONrol of the MCP chips: (EXPERIMENTAL! Testing needed.)
  INTCON=1 << If any of A or B input IO-bank pin changed, both INTA and INTB is triggered

Change Log 2022-09-07 (Y-M-D) Version: 2.3.8.20220907

by László Szakmári (www.pizzaprogram.hu)

• Changed Interrupt initialization of the MCP chips: (EXPERIMENTAL! Testing needed.)
  MIRROR=1 << If any of A or B input IO-bank pin changed, both INTA and INTB is triggered
  ODR=1 << Not only "Active-Low" state, but both "High/Low" input changes are triggered

Change Log 2022-06-07 (Y-M-D) Version: 2.3.7.20220607

by László Szakmári (www.pizzaprogram.hu)

• WARNING! Naming of commands and msg values changed !!! (No more Capital beginnings.)
  "All0" -> "all0"
"All1" -> "all1"
msg.AllStatesRaw -> msg.allStatesRaw
  ... also fixed name convention at source code, like OnOFF -> on_off
  Read more here

• If read-interval is set to 0 it will clear any running timer.

Change Log 2022-06-06 (Y-M-D) Version: 2.3.6.20220606

by László Szakmári (www.pizzaprogram.hu)

• BUG Fix: Too long read time caused a (.warning) error instead of increasing the timer interval x2.

• Enh.: If the last read time is shorter than interval, it resumes the timer at original interval.

Change Log 2022-03-26 (Y-M-D) Version: 2.3.5.20220326

by László Szakmári (www.pizzaprogram.hu)

• PCF chips show now correct Address -at Main-Chip setup. Fixed.

• Fixed "interval too short" auto-increase happaning if "interrupt-triggered" read occures

• Added examples

Change Log 2022-03-25 (Y-M-D) Version: 2.3.3.20220325

by László Szakmári (www.pizzaprogram.hu)

• Changed msg.pin and msg.state to lower case.

Change Log 2022-03-22 (Y-M-D) Version: 2.3.2.20220322

by László Szakmári (www.pizzaprogram.hu)

• you can set 1-1 node only pro 0-7 or 8-15 and control via msg.Pin= and msg.State= if msg.Payload=-1

• fixed consol.warning bug if Timer set = 0ms.

Change Log 2022-03-21 (Y-M-D) Version: 2.3.1.20220321

by László Szakmári (www.pizzaprogram.hu)

• Fixed bug: on input change payload was always "true".

Change Log 2022-03-19 (Y-M-D) Version: 2.3.0.20220319

by László Szakmári (www.pizzaprogram.hu)

• FIRST OFFICIAL RELEASE

• Enhanced html help of the node

• fixed bugs (like: partial Deploy did not clear prev. instances from context)

Change Log 2022-03-03 (Y-M-D) Version: 2.3.0.20220303

by László Szakmári (www.pizzaprogram.hu)

• Added PCF8574 + PCF8574A chip support. Both In + Out.

• Fixed Naming of PFC... to PCF... (the original code was spelled wrong!).

• Detailed Logging to consol can be turned on/off with const log2consol = False; and timerLog = false;

• Fixed Input Bugs. Now stable.

• Fixed bug if same chip had both in+out pins mixed.

• Fixed crashing of Node-red if chip or I2C bus was suddenly removed from system.

• Inject (Interrupt) trigger adds extra values to msg. [] ... see help

• New Github upload. (PFC false-named one got deleted)

Change Log 2021-01-11 (Y-M-D)

by László Szakmári (www.pizzaprogram.hu)

• !!! IMPORTANT CHANGE: -- [ x ] Inverse is now affecting Output too ! (Some relay boards are functioning "the opposite way", turning ON if pin is Low.)

• Changed Bus open/close behaviour. Separate open before/after each read/write operation block. (This way no more non-stop opened bus > no more NodeRed crash if unexpected disconnect.)

• Fixed other NR crashes: Added Error handling (try - catch) for each i2c bus operation.
  Each operation has it's own value to report proper error text. (Like: "Bus opening failed", ... etc) (But execution time increased from 8ms to 12ms on Raspberri 4)

• Fixed 16pin array initialization (16x null)

• Added multiple/same pin initialization error handling. (Highlander: "There Can Be Only One" :-D )

• Added lots of comments and constants to JS file (like IOCON, IODIR_A, etc...)

• Changed icon to a chip-like one. (font-awesome/fa-ticket)

• Faster initialisation: if set to output >> skips pullup & invert writes.

• Prevents the input-timer to run if the previous function is still running.

• +2 states of a node and color change of Off: On=green Off=grey Uninitialised=yellow Error=red

• Does not starting input-timer, if there are no input nodes available.

• Auto-increasing read-interval if < 15ms or if reading took too long.

• If error occured during read-timer >> changing interval to 5 sec >> if normal again >> changing back

• Dokument + Code changes: -- Pretty print of JS code (inline) -- All local variables start now with _underline -- Many comments + constants + references added to code -- Fixed help in mcp_pcf_chip.html file

Change Log 2021-09-12 (Y-M-D)

• Fixed input

• Add input trigger to handle interrupts. If msg.payload = True >> and succesfully read

  msg.immediateReadSuccess = true. If any error:Result = false

• Limit debounce timeing to max = interval - 20ms

• debounce is not starting if =0

Change Log 2021-11-11 (Y-M-D)

• Node name changed from MCP23017chip to current ,mcp_pfc_aio v2.1.0 ( AIO = All in One IO = Input Output )