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In accordance with the above, to program/reprogram a segment of the flash memory one
needs to execute the following sequence:
With the FPGA booted ("Fail" LED off):
1. Set the rotary switch to a P position pointing to the desired segment => the red "Fail"
LED should turn on.
With VM-USB off or the FPGA failure to boot:
1a. Cold-boot VM-USB with the rotary switch in the desired P position.
2. Send successively the 830 sector programming buffers containing a complete
configuration file of the XC3S400 FPGA to the USB port in bulk transfer mode,
while specifying the data length as 518 bytes and allowing at least 30ms wait time
between the consecutive buffers.
3. Send an FPGA "reset toggle" buffer, or cold-boot VM-USB in the corresponding C
mode. A successful boot will be indicated by the "Fail" LED turned off.
The use of the flash memory programming capability is largely facilitated by the availability
of dedicated libxxusb functions xxusb_flashblock_program and xxusb_reset_toggle, as
illustrated by the following sample codes written in Visual Basic:
'Flash memory programming
For i = 0 To 829
k = i * 256 + 1
ll = xxusb_flashblock_program(EZHandle, bytes(k))
DLY (30) '30ms delay generator
Next i
'Releasing or setting the FPGA reset:
ll=xxusb_reset_toggle(EZHandle)
In the above two samples, EZHandle represents the USB handle of the VM-USB and bytes()
is an array storing the desired FPGA configuration file (220 kB).
WIENER, Plein & Baus GmbH
55
www.wiener-d.com
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