--- Quote Start ---
Porting the Jam player is pretty simple. I use it for programming EPC2 EEPROMs (used with FLEX10K FPGAs), and for programming MAX II CPLDs.
Porting the Jam player basically involves supplying toggle I/O routines for controlling the JTAG pins.
--- Quote End ---
I had more times to check the source code of JAM STAPL and compile it for UNIX. Since I need to port the code for embedded linux board with OMAP3. I configure the MUX pins of the ARM processor to associate to specific GPIO that I will use for TCK,TMS,TDI,TDO.
So now what I need to understand in the jbistub.c from JAM is why :
1- Before each read it does this write of 0x7E:
ch_data = 0x7e;
write(com_port, &ch_data, 1);
THIS mean that 01111110 and since
TCK = bit 0
TMS = bit 1
TDI = bit 6
TDO = bit 7
So TCK = 0, TMS = 1, TDI = 1 and TDO = 0
So why doing this before each read? Is it only specific to parallel port of JTAG specific?
From this document page 9
http://www.altera.com/literature/hb/max2/max2_mii51015.pdf 2- Second question why looping 100 for the read? parallel port specific or JTAG? Maybe a validation to simply be sure to read the value and not missing it because the read is done to fast??? That seem to me a poor way to code this?
for (i = 0; (i < 100) && (result != 1); ++i)
{
result = read(com_port, &ch_data, 1);
}
if (result == 1)
{
tdo = ch_data & 0x01;
}
else
{
fprintf(stderr, "Error: BitBlaster not responding\n");
}
Regards,
Kevyn-Alexandre Paré
Honored Contributor
