Ooops, I missed the topic, sorry about that!
I guess I don't see the problem then....sorry about that as well :-)
/Henrik.
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Re: Port alias in Port Expanders (MCP23S17)
Ooops, I missed the topic, sorry about that!
I guess I don't see the problem then....sorry about that as well :-)
/Henrik.
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Re: Port alias in Port Expanders (MCP23S17)
Henrik-
I may have been too hasty in my description ( I am back on my home project) as I am stumped. I had used the I2C version of this part a while back and have it working. Now I am trying to use the SPI version (MCP23S17) for its speed and I can't seem to figure out how to get from a byte indicating which bit to turn on for the MCP23S17 part.
Lets say I receive a var and it's value is $E. This var needs to tell the MCP23S17 that the 15th output should turn on. Now that is GPB-7 on the MCP23S17.
I have a routine that converts HEX to DECIMAL (thanks to this forum years ago) and that works fine, how to I get a single decimal to go to the correct port on the MCP23S17?
My code works fine to send a binary string (easier to visualize for me) to the MCP23S17 but I can't seem to get the finesse of going from 1 hex or 1 dec char to the right bit output.
I have looked through the forum and I have seen yours and others pointing to OUT.0[var] which gets to the VAR-position of the OUT variable but as I have 2 eight bit outputs I am stumped......
From the MCP23S17 datasheet it looks like it may be addressed as one 16 bit output, is that accurate? Any suggestions?
Some code below:
Code:OutA var byte OUTtest:'------------ TEST OutA=$1 'Simulate number from serial comm, example '1' K=OutA 'Sets up the conversion from hex to decimal gosub H2D 'Performs the conversion debug "After H2D K=",dec1 K,13 'Double-check what the sub did k=k-8 'try this for a pointer OutA_DataOut=OutA.0[k] 'Try to set the correct bit out of 8 to turn on and pass to OutA_DataOut which is passed to the MCB23S17 OutA_MCPReg = OLATA 'Sets up PORTA output ' OutA_DataOut=%11111110 'This works by setting individual bits, but not good for what I want to do gosub SEND_OutA_2317 'Send to the expander pause 10 'wait a bit OutA_MCPReg = OLATB 'Sets up PORTB output OutA_DataOut=%01111111 gosub SEND_OutA_2317
"If we knew what we were doing, it wouldn't be called research"
- Albert Einstein
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Re: Port alias in Port Expanders (MCP23S17)
Henrik-
Also forgot to mention that in the older I2C design I had 8 bits of inputs and 8 bits of outputs on one 2317.
This new design is all outputs - I thought it would be easier!
Not so much......
Regards,
Steve
"If we knew what we were doing, it wouldn't be called research"
- Albert Einstein
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Re: Port alias in Port Expanders (MCP23S17)
Sounds like what you're looking for is the DCD operator:So, perhaps something:DCD returns the decoded value of a bit number. It changes a bit number (0 - 31) into a binary number with only that bit set to 1. All other bits are set to 0.
B0 = DCD 2 ' Sets B0 to %00000100
Henrik.Code:OutBits VAR WORD GPA VAR OutBits.BYTE0 GPB VAR OutBits.BYTE1 Outbits = DCD $E
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Re: Port alias in Port Expanders (MCP23S17)
Thanks I will try that!
I have made some progress but I still need a way to get from 1 byte which will tell me which of the 16 outputs to turn on.
Current test code:
This gives me what I want - EXCEPT - for that I have to resolve 1 byte into a word and figure out how to get the pointer right........Code:OutA=$FFFE 'Initial value for word var OutA_hi=OutA.highbyte 'Splits into hibyte OutA_lo=OutA.lowbyte 'And into low byte of the word var OutA_lo.3=0 'Bit mod OutA_hi.5=0 'Another bit mod OutA_MCPReg = OLATA 'Sets up PORTA output OutA_DataOut=OutA_lo 'Sets up data to be pushed to the MCP23S17 as the low byte gosub SEND_OutA_2317 'Send it pause 10 'Wait a bit OutA_MCPReg = OLATB 'Sets up PORTB output OutA_DataOut=OutA_hi 'Sets up data to be pushed to the MCP23S17 as the hi byte gosub SEND_OutA_2317 'Send it
starting with a byte var which has a value from 0-15 to a specific bit on the MCP23S17 still evades me I am afraid.
"If we knew what we were doing, it wouldn't be called research"
- Albert Einstein
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Re: Port alias in Port Expanders (MCP23S17)
Henrik-
Thanks for the assist, but I don't think I can use that idea. There are some outputs which will be already active which another serial command comes in and I will need to add to the already ON LEDs with whatever new ones are called for.
There is a serial comm line coming into the project and on that serial comm is a byte which will let me know which output(s) to turn on. Some may or may not be on.
So, I will have to logically AND them to get the correct outputs on when they need to be.
"If we knew what we were doing, it wouldn't be called research"
- Albert Einstein
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Re: Port alias in Port Expanders (MCP23S17)
Why does this not work?
OutA.12=0 doesn't gen an error but it nor the other (OutA.15=0) turns ON an LED?????
Code:OutA=$FFFE 'Initial value for word var OutA_hi=OutA.highbyte 'Splits into hibyte OutA_lo=OutA.lowbyte 'And into low byte of the word var ' OutA_lo.3=0 'Bit mod - WORKS ' OutA_hi.5=0 'Another bit mod - WORKS OutA.12=0 'Why doesn't this work? OutA.15=0 'Or this? OutA_MCPReg = OLATA 'Sets up PORTA output OutA_DataOut=OutA_lo 'Sets up data to be pushed to the MCP23S17 as the low byte gosub SEND_OutA_2317 'Send it pause 10 'Wait a bit OutA_MCPReg = OLATB 'Sets up PORTB output OutA_DataOut=OutA_hi 'Sets up data to be pushed to the MCP23S17 as the hi byte gosub SEND_OutA_2317 'Send it
"If we knew what we were doing, it wouldn't be called research"
- Albert Einstein
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