Can a Jeelabs Output plug be used as 4 bit INPUT and 4bit OUTPUT ?

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gyrolen
I would like to use the Jeelabs Output Plug for 4 bits OUT and 4 bits IN.
When I run the program below, I get no change when jumping a resistor across 3v or Gnd to P0-7, using the 12 pin pad on the outside of the darlington 2803 chip.
The 12pin access plug is on the other side of the 2803 Darlington chip, can this chip be read from as well as write to?, I have had no success.
I have cut a track between then I2C-p7 and the 2803, and put an input wire to the P0-7 pins of the I2C chip, but had to increase voltage to 5V for a TTL -CMOS to change state. I have tried this and it produces some results but very difficult to solder, and seems to cause problems. Is there a better way to do this?, thanks.
#include #include #include
int sWas =0; PortI2C myport (1 /, PortI2C::KHZ400 /); DeviceI2C expander (myport, 0x26); // also works with output plug if 0x26/0x27 enum { MCPIODIR, MCPIPOL, MCPGPINTEN, MCPDEFVAL, MCPINTCON, MCPIOCON, MCPGPPU, MCPINTF, MCPINTCAP, MCPGPIO, MCPOLAT };
void setup() {
```
    expsetup();
    Serial.begin(9600);
    Serial.print("\nREARGUARD-MAIN;
    Serial.println("LRBT\tLIGHTS");
```
} void loop() { checkSwitches(); }
void checkSwitches() { // when reading remember resets output port afterwards ? byte outputPort=expread(); // if (outputPort == 0) return; if (sWas !=outputPort){ Serial.println(outputPort,BIN); sWas = outputPort; delay(500); } }
static void expsetup () {
```
    expander.send();
    expander.write(MCPIODIR);
    expander.write(0);// to 4 bit out-bottom 4 in was =0
    expander.stop();
```
}
static void expwrite (byte value) {
```
    expander.send();
    expander.write(MCPGPIO);
    expander.write(value & 15); // top 4 bits for out
    expander.stop();
```
}
static byte expread () {
```
     expander.send();
     expander.write(MCPGPIO);
     expander.receive();
     byte result = expander.read(1);//x & 240;// bottom 4 bits for in was 1
     expander.stop();
     return result;
```
}
Posted 01/08/2010 21:32:48
stef007

Hmmm I don't think the outputplug is intended to provide inputs. So indeed, you will have to do some hardware patching. The expander plug uses the same IO expander chip but in case of the outputplug, the io expander's IO pins are connected to the inputs of the darlington array. So the "input" sensing capability is lost there. But I suppose you already knew this.
You don't want to use the io expander plug because you need to handle bigger voltages and/or bigger currents? Why not use the IO expander plug and add a darlington transistor for each output that requires more current?

Posted 01/08/2010 22:14:22
gyrolen

Yes probably the expander plug, would be better, but I have an urgent job and don't have the time to order an expander, and would still have the CMOS-TTL problem. Yes the expander uses the same I2C chip 23008 as expander, so that is why I thought to connect to the track between the 23008 and the input of the darlington but very difficult to solder wire to pins D4-7, and also that is where I run into the problem of TTL to CMOS. The inputs are switches which if held high via 3V supply is not high enough to show a transition from high to low on the 23008 (changes to low ok,but never shows high),incidentally it drives a led at the same time, which drops 1V or so. However if I use 5V from the P pin it works ok on 2 switches pins 5,6 but not on 4,8, I don't understand. Maybe the 23008 pins out 4,8 are damaged. It is beyond my basic electronics knowledge.

Posted 02/08/2010 10:28:31

joop

Maybe I missed it, but don't you need,pullup resistors on input ?

    example  pins 0 1 3 5 7 are output pins 2 4 6 are input (need pullup  can be done
                                                             by software MCPGPPU)
    void SetupIOdirection(void)
       {
       expander.send(); 
       expander.write(MCPIODIR); // 0101.0100   0 = output      7654 3210
       expander.write(0x54);      // pin 0 1 3 5 7 I/Oplug outp 0101.0100
       expander.stop();           // pin 2 4 6     I/Oplug inp    
       }

    void SetupIOpullupresistors(void)
       {
       expander.send(); 
       expander.write(MCPGPPU); // 0101.0100   1 = pullup 100k 7654 3210
       expander.write(0x54);     // pin 2 4 6     I/Oplug inp   0101.0100
       expander.stop();             
       }


				Posted 02/08/2010 17:56:12


	
		
			
								
					gyrolen

				
			
			
				
Thats it, excellent, it works, thanks Joop.



				Posted 02/08/2010 20:56:05