[ Specified attachment is not available ]Raulm, you're on the right track I think. Just to clarify a bit more: the FTDI USB chips are generic units that can be used as UARTs, or as JTAG, or as BDM ports. Or I2C or SPI or whatever. Or as a mix thereof. The FT2232H has two 8 bits ports, the FT4232H has 4. So if you have two serial ports and a BDM port, and want to use them all at the same time, then the FT4232H is the best choice. For now I think you only need the BDM function with maybe one serial port (because you like to copy screen dumps to your PC?).
JTAG is irrelevant here even though the legacy PowerPC CPU XPC860 has JTAG, you cannot really use it in a TDS3000 because there's a pin for it (TMOD) soldered to a power supply rail, right under the BGA, so pretty much impossible to cut that line. But the BDM (a legacy Motorola/Freescale/NXP backdoor debug port, somewhat like JTAG but not quite...) interface does has its pins wired to the expansion connector. So that we use. As per the schematics shared in this forum, but here it is again in pdf attached. Be aware of different styles for pin numbering - that's because it's a PCB edge connector in this design, not the official 100 pin Molex connector.
Besides BDM, the TDS3000 100 pin expansion connector has two TTL level serial ports. One is without CTS/RTS handshake lines and is a VxWorks monitoring / ex factory testing line, the other is the serial (RS232) port that's on user i/o modules like TDS3VM and others. The latter is what you listed. It's also the port for a serial printer and for
https://www.eevblog.com/forum/testgear/tds-1000-2000-3000-bw-hack/. That's a hack at application level. The BDM port is about diving at a much lower, deeper level, peeking and poking right into the hardware, halting and single stepping the PowerPC CPU. Or reflashing the ROMs. Or peeking into the other i/o on board. Or pinging its I2C bus that goes to the front panel.
If for you it's only about editing the NVRAM via BDM, then you don't need any of these serial ports now. Just BDM.
The relevant pins for BDM are: TDO, TDI, TCK, SRST, HRST, IRQ6 and GND. Those go to a MAASP port on the FTDI chip. The program I shared assumes you wire the 8 TTL level bidirectional I/O lines from either a FT2232H or a FT4232H, like this:
ABUS0 -> TCK
ABUS1 -> TDI
ABUS2 -> TDO
ABUS3 -> not used
ABUS4 -> SRST
ABUS5 -> IRQ6
ABUS6 -> HRST
ABUS7 -> not used
GND -> GND
Or, as it's coded in the .h file,
#define MASK_DSCK 0b00000001
#define MASK_DSDI 0b00000010
#define MASK_DSDO 0b00000100
#define MASK_SRESET 0b00010000
#define MASK_FRZ 0b00100000
#define MASK_HRESET 0b01000000
#define MASK_NEN245 0b10000000
I've mixed up naming conventions for JTAG and BDM - the XPC860 uses many of the same pins for either BDM or JTAG. But you get the idea I think.
second_life_tds3000_light_FT4232H.pdf (320.37 kB - downloaded 218 times.)