dfu-programmer says: "no device present" when PD pins are tied low

Go To Last Post
5 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I'm using PD 4-7 as SPI lines to another device and I've found that dfu-programmer won't work if any of the lines are connected to anything, even tied low. Do I need a current limit resistor? I've tried 4.7k pull-ups.

- Dan

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Don't have a problem when using port c as the SPI.

- Dan

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

When you share an SPI port with peripheral devices and programming, it is common practice to add a series resistor in the MISO line, between the peripheral and the rest of the SPI  network. I think I have seen a few Kohms.

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I have a 100 ohm current limiting resistor in between all signals and its only on the AVR side of MISO that's getting a reduced voltage sometimes.

Attachment(s): 

- Dan

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I finally bothered to read the manual for the MattairTech MT-DB-XT and on page 10 it says:

 

"The PDI/SPI header can be connected to an external PDI programmer/debugger.
Alternatively, this header can be used for SPI communications (master or slave).
The image below shows the PDI configuration, which is the default. To convert the
header to SPI mode, close J9 and J11, then change J8 and J12 to the alternate
positions. This will route 4 header pins to pins C4 – C7 of the XMEGA (there is a
SPI peripheral here). Pin C4 can be used as a chip select (or as a slave select if in
slave mode). See schematic for pinout information."

 

So maybe that's why it wouldn't work.

 

(I haven't tried the SPI for PORTD yet).

 

- Dan