Forum: µC & Digital Electronics AT91SAM7S USB SAM-BA Problem

Author: Nazmus Sakib (Company: Time & Space) (sakibnaz)
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I am trying to enable the USB SAM-BA to program my AT91SAM7S Chip.
I don't have any Evaluation Kit, I made a custom Header Board and trying 
to Program the MCU via USB. The Chip is working. I can program the Chip 
with RS232 SAM-BA.

The Problem I am getting in the USB Pull-Up connection:

USB D+ ---> 1.5K ----> 3.3V

My Windows PC is reporting "Device Not Recognized".

Any suggestion .... Thanks in advance.


Author: Pavel (Guest)
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Sorry my bad English, I am russian ...

To use SAMBA, you must first do 2 steps:
1. Power on your board, connect ERASE pin to +3.3v directly for 1-2 sec. 
This will erase all CPU's flash memory.
2. Power off board, disconnect ERASE pin from 3.3v, connect TEST pin to 
+3.3v directly.
3. Power on board, wait 15-sec. In this step CPU rewrites SAMBA from 
internal ROM to Flash.
4. Power off, disconnect TEST pin from 3.3v.
5. Power on board. SAMBA is works. If you connect board to USB, your 
computer will detect new hardware and ask driver. Driver is available in 
SAMBA program installation.

Note, you must have external 1.5k pull-up resistor on D+ pin. AT91SAM7S 
does not have internal resistor. You can see Olmex dev board schematics. 
There are 2 variants - fixed pull-up and disconnectable by PA16 pin.
You always must use only PA16 for this - required by SAM-BA bootloader.


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