New Dev Kit Request: G4 on a 200 pin SODIMM module

[kster59]

I'd love to use the G4-512 chip but the development costs for a 6-8 layer board + BGA professional paid assembly makes it cost prohibitive for prototyping. I usually go through several iterations of PCBs before getting to the final product so this would be extremely expensive and slow process. As XMOS is built for rapid prototyping and fast to market, I highly recommend making an inexpensive module available.

Others have suggested 40pin dips but I think that has limited use as one can just hand solder L1 chips.

My suggestion to XMOS is to make a 200pin SODIMM daughterboard exactly the same as the XC-1A (include the FT2232D USB+UART, AT25DF041A flash, LTC3417 regulator), exclude the LEDs/Speaker/Pushbuttons and breakout more of the I/O pins.

200pin SODIMM sockets are very inexpensive at around $2 each at Digikey as they are standard for notebook memory (interestingly both 144pin and 204pin cost more) and quite small.

This would be an ideal solution to allow for inexpensive rapid prototype double sided prototype boards.

The XMOS XC-1A is a great board but is very difficult to put into an end product and is only good as a Dev board. Even as a dev board, not that many pins are broken out.

The cost of the XC-1A is also excellent value at $69 in qtys > 2. I think only XMOS can make these boards due to their reduced pricing:
G4-512 chip = $30
LTC3417 chip = $5
FT2232D chip = $5
Flash chip+misc = $5-10

Basic chips alone would cost an average user $45-$50 excluding the 6-8 layer PCB and assembly.

If the G4 chip were available as a SODIMM module with the extra components at around the same price ($50-70) I'd buy at least a few hundred to use in my designs for initial sampling then outsource the board design to reduce cost as the quantity increases.

I would imagine this to be pretty simple task of deleting the extra LEDS and pushbuttons and rearranging the components to fit the SODIMM format.

Any comments?

[lilltroll]

I really like the DIMM idea, since I used DIMM-PC earlier.
I was able to make a very small IBM-PC comp. small computer with my own 2 layer design.

Isn't it better to use an external XTAG for programming - so we can skip the extra cost for the FTDI chip ?

[kster59]

The FT2232D gives both USB and JTAG functions so the JTAG is basically free. It's on the XC-1A already so I would assume it's more work to get rid of it than keep it.

I find having integrated FTDI USB to be critical on a dev board. I have both an XK1 and and XC-1A and the XK1 is basically useless for me due to no easy way to communicate data with the host pc.

An XTAG2 adds $50 to the cost of any project which is pretty steep if you can just include the FT2232D. It's not as critical now that I figured out how to use libflash to do in field updates without a JTAG.

I'd still buy it without the FT2232D but it would save a lot of hassle and also save 4 JTAG pins that could be used for I/O.

[lilltroll]

OKi, the XTAG2 is missing the USB virtual com driver for the moment, but the XTAG1 has it !?

My idea was that you will only need one programmer for 100 DIMM cards = reducing price for the DIMM.

[lilltroll]

Kaster - do you have a good auto-router ??

Could you import the existing design - delete all Toys - and see if the router can find the solution for a SODIMM.

A proof of concept is always good.

[kster59]

I'm not familiar with the XTAG1.

The XK1 comes with an XTAG2.

The XC-1A has a FT2232D which acts both as the jtag and ft232 chip. If it were up to me I'd prefer putting the ft2232d in ft245 mode since there are a lot of left over io pins on a G4. Better yet I'd put a FT2332H for high speed USB at no increase in BOM.

The Ft2232d is around $6 and the plain Ft232 is around $4.50 so the price difference is pretty low.

FTDI drivers are available for most platforms and easy to program using either virtual comm or D2xx.

I run Altium Designer and can't import the designs but I did draw out the L1 and G4 devices already. I don't think a proof of concept would help as making the board seems pretty trivial with the resources/motivation. Sodimm cards can be made as tall as you want and still fit the socket with the right cut ins.

It seems pretty easy to just move the components around to fit the new format and make it.

We just need to encourage XMOS that it would be high demand product and no extra cost beyond the XC-1A board.

[GeorgeIoak]

@kster59: I'm just getting started with a new design and am also using Altium Designer. I wasn't able to successfully import the reference symbols or designs even though AD has some pretty good import utilities. Would you mind sharing your library? I also hope that XMOS could post in a more "usable" format.

Thanks,
George

[kster59]

Sorry PCB designs are not my property to share but making the components in Altium is pretty trivial. I don't have an L2 drawn yet but L1 and G4 footprints take about 2 minutes to generate with the IPC generator.

[GeorgeIoak]

I didn't think the new 124-QFN was a standard part that could be generated with IPC generator. I just figured I'd ask before I started to reinvent the wheel ...

[kster59]

Ya I usually just pay someone else to draw those non standard parts for me :)

QFP and BGA parts are no problem with the IPC of course.