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MCP2140A: IrDA communication with PC

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I'm having some major trouble with my IR connection with the computer. I got the MCP2140A because it was supposed to take care of the IR stack protocol needed to communicate with the PC, but I'm having trouble getting the computer to recognize it (it usually recognizes it for a second, the doesn't see it anymore despite the fact that it keeps sending IR pulses).

I copied most of my schematic from a demo board of theirs, but still nothing. I don't think the MCU is even needed for the computer to recognize the chip. Just hoping someone out there can see what I'm doing wrong!


(The 6 pin connector is for the MCU programming header)
 

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DirtyLude

Well-Known Member
I don't understand. How are you connecting this to your PC?

Your schematic has a connection between the chip and a PIC. I don't see any connections to anything else.

EDIT: Are you trying to connect this to the computer over that serial connection? Are you using a level converter for RS232?
 
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I'm trying to connect to the computer through the IR port on the computer - mine has an IR window in the side of the computer. I've connected to it using a demo board, but not with my own setup.
 

DirtyLude

Well-Known Member
Reading up on it, it's confusing me more than anything. I've implemented IrDA, but only between uC's, so technically not real IrDA, since I don't need to conform to anything but the PHY layer.

It looks like it's supposed to implement irCOMM itself, but I'm not certain. Have you tried looking at the sample frimware from their demonstration boards, like the logger and temp sensor?
 
I have the temperature sensor demo board, which works like a charm. I've used it to send and receive info through hyperterminal (after installing a virtual com port). There's no demo board with the MCP2140A, the temp sensor board uses the older version of the chip, the MCP2140, which is similar.
 
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Rabbitsfot

New Member
Check the PHACT pin...

Check the state of the PHACT pin. It will tell you if the chip's state machine is in the discovery state or not. Check that you have a pull up on that pin since its OC.

Check the DSR pin which will tell you if you are getting a link from the chip.

Confirm that the DTR and RTS pins are low.

In, general read the manual and ask yourself if each pin of the part is in the state it should be according to how the part operates as described by its data sheet.
 
Check the state of the PHACT pin. It will tell you if the chip's state machine is in the discovery state or not. Check that you have a pull up on that pin since its OC.

Check the DSR pin which will tell you if you are getting a link from the chip.

Confirm that the DTR and RTS pins are low.

In, general read the manual and ask yourself if each pin of the part is in the state it should be according to how the part operates as described by its data sheet.
Thanks - have you used this chip before? I keep the DTR at GND, but I've been trying the RTS both ways because I wasn't sure whether to keep it high or low, so I'll keep it low.
 
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