Library attached for using the MCP23018 16 bit I2C I/O expander chip. It's similar to the MCP23017, but the pinout is different and it has open drain outputs (not push-pull).
The I2C bus address is set by cahnging the voltage on the address pin. The default address in the library is 0 (address pin connected to Vss) but this can be overriden by defining MCP23018_Addr in the program code. At present, only 1 device on the bus is supported.
I built this chip onto a board to use with a keypad so there are functions included for reading the value of a 4x4 keypad. The schematic is below - if you have something different then you will need to alter the library to suit, and also the keypad map.
I am waiting for some similar I/O expanders which I will add into the library in due course.
Interesting Peter. I just remembered I got five mcp23017 chips that I haven't used and I'll ckeck your code as first post I've seen for similar. I thought of many uses including driving a glcd with lots of pins.
Thanks for sharing. Nice one.
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True Chris. I hadn't noticed. I forgot I had the chips to until I saw Peter's post. Thanks for the update.
They look fast-
• High-Speed I2C Interface (MCP23017):
- 100 kHz
- 400 kHz
- 1.7 MHz
• High-Speed SPI Interface (MCP23S17):
- 10 MHz (maximum)
•
from uchip
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Excuse me, if that comes across as a schoolmaster.
The new homepage has a search function, which spits out the following when searching for 23017:
HARDWARE ACCESSORIES
mcp23017 i2c to serial a library that supports the i2c to serial functions.
mcp4xxxdigitalpot digital pot a library that supports the mcpxxxx
range of digital potentiometers. mcp7940n clock
The description of all Libraries are available online, one have to find only ;-)
Last edit: bed 2017-12-02
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Sorry if I'm intruding, I have a pair of MCP23S17 expander but I do not know how to use them. On the pinout I see that it uses an SPI interface with commands on CS, SCK, SO, RESET.
Is there a simple demo where to learn?
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I do not see a demo for these chips - but, I am sure one of the guys in this thread will create some demos - I can then pick up and put in the GitHub library.
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You could try changing the mcp23017 includes..there a new one in projects, i2c to spi. See demos/spi. Are they the same operation ie setting address tieing pins?
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The MCP23S17 has the same pinout except the NC/I2C pins are swapped for a CS and the SPI connections.
Registers are the same, but obviously it sends SPI packets instead of I2C. Figure 3-3 of the datasheet is great for explaining how the I2C interface works but I can't see a corresponding one for SPI.
I've only tried SPI devices a few times and failed to get them to work on every occasion so stick to I2C.
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I'll have a go at converting existing code from the forum to spi. 5 minute job :)
The spi stuff I use with gcb works fine if I wire it correct. Any problems have been 3.3V or 5V logic levels.
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Library attached for using the MCP23018 16 bit I2C I/O expander chip. It's similar to the MCP23017, but the pinout is different and it has open drain outputs (not push-pull).
The I2C bus address is set by cahnging the voltage on the address pin. The default address in the library is 0 (address pin connected to Vss) but this can be overriden by defining
MCP23018_Addrin the program code. At present, only 1 device on the bus is supported.I built this chip onto a board to use with a keypad so there are functions included for reading the value of a 4x4 keypad. The schematic is below - if you have something different then you will need to alter the library to suit, and also the keypad map.
I am waiting for some similar I/O expanders which I will add into the library in due course.
Last edit: Peter 2017-11-19
Keypad demo video here:
And an image of the BodgeBoard™ used to add in the pullup resistors which were omitted from the PCB design!
And here's a simple LED chaser demonstration, showing how to use the port as an output.
Last edit: Peter 2017-11-19
@Peter. May I lift the library (from here? or, do you have a later version?) and demos etc and include in the next distribution?
Let me know please.
Interesting Peter. I just remembered I got five mcp23017 chips that I haven't used and I'll ckeck your code as first post I've seen for similar. I thought of many uses including driving a glcd with lots of pins.
Thanks for sharing. Nice one.
Strange that it is the first you have seen Stan.
The .../GreatCowBasic/Include folder has:
MCP23008.h
MCP23017.h
and
PCF8574.h
So the three most common port expanders have built in support alraedy.
The MCP23018 will be a nice addition.
True Chris. I hadn't noticed. I forgot I had the chips to until I saw Peter's post. Thanks for the update.
They look fast-
• High-Speed I2C Interface (MCP23017):
- 100 kHz
- 400 kHz
- 1.7 MHz
• High-Speed SPI Interface (MCP23S17):
- 10 MHz (maximum)
•
from uchip
Excuse me, if that comes across as a schoolmaster.
The new homepage has a search function, which spits out the following when searching for 23017:
The description of all Libraries are available online, one have to find only ;-)
Last edit: bed 2017-12-02
I could not find a mcp23017 demo. I can find how the mcp23017 works but not how to use the include without examining it.
We must have missed this device.
@Stan. Are you up to writing a simple example that we can publish?
I have mcp23017 chips if they are similar enough. I thought about using the 23017 to drive 2 stepper motors
Sorry if I'm intruding, I have a pair of MCP23S17 expander but I do not know how to use them. On the pinout I see that it uses an SPI interface with commands on CS, SCK, SO, RESET.
Is there a simple demo where to learn?
I do not see a demo for these chips - but, I am sure one of the guys in this thread will create some demos - I can then pick up and put in the GitHub library.
thank you so much. I will follow the topics.
You could try changing the mcp23017 includes..there a new one in projects, i2c to spi. See demos/spi. Are they the same operation ie setting address tieing pins?
The MCP23S17 has the same pinout except the NC/I2C pins are swapped for a CS and the SPI connections.
Registers are the same, but obviously it sends SPI packets instead of I2C. Figure 3-3 of the datasheet is great for explaining how the I2C interface works but I can't see a corresponding one for SPI.
I've only tried SPI devices a few times and failed to get them to work on every occasion so stick to I2C.
I'll have a go at converting existing code from the forum to spi. 5 minute job :)
The spi stuff I use with gcb works fine if I wire it correct. Any problems have been 3.3V or 5V logic levels.