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ADUC845 Bootloader

Good morning to everyone:

I have a prototype made on the basis of the evaluation board of micro ADUC845/6/7 in which I have added a driver 485 and an operational amplier in the DAC output. Below is the drawing.

The problem I find that putting the PSEN pin low level (GND) and do the reset, the bootloader does not start. I'm using the original TTL to 232 cable of the evaluation board to communicate with the PC (I take the power for this cable from AVDD and GND.

I have the same configuration (I think) mounted on the evaluation board and everything works fine.

What could be wrong? I would appreciate your help.

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  • Hi  Ascell

    I have not worked with RS485 recently but I believe you can not use it in this situation.  In your cicuit diagram you have connected the MAX485 enable pins to a port pin but what is going to control this pin?  From your description it seems you have this pin level high so that the MAX485 will drive the twisted pair but can not receive from the twisted pair.

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  • Hi  Ascell

    I have not worked with RS485 recently but I believe you can not use it in this situation.  In your cicuit diagram you have connected the MAX485 enable pins to a port pin but what is going to control this pin?  From your description it seems you have this pin level high so that the MAX485 will drive the twisted pair but can not receive from the twisted pair.

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