@AreYouLoco mentioned SLE4442 smart cards and 2 wire mode. To prep for that I bought several smart cards:
SLE4442 & 4428 (passcode card that self destructs after 3 failed password attempts)
24C02 & 24C16 (simple I2C EEPROM on a card)
Yes, I have a quote for custom printing
KF-011C seems like THE cheap and common smart card socket. This is a common name for multiple Chinese manufacturers of the same part. It appears to be a copy of a part from a company in Taipei.
I made up a simple adapter for it. You might notice that the power and ground are also to IO pins, instead of the Bus Pirate power and ground. That’s so we can control the power with an IO pin and attempt to glitch hack the passcode card. It also makes it universal - cards that don’t follow the typical pinout can still be probed.
I almost had the 10 prototypes assembled without testing and put them up for anyone who wants to try. The office is busy getting the Bus Pirates out though, so I didn’t want to bother them this week.
I should be able to test early next week, then we can have production boards maybe a week after? It’s pretty simple, I think I can send it to the hand soldering people, no need for a stencil and pick and place.
Finally got the sim card holder sorted. That’s kind of a wild west.
I did try to get 8 pin holders for everything, but 6 is standard, cheap, and comes in the most form factors
I got the simplest connectors possible. I did not want spring loaded or locking, or flip tops that could break or be annoying to use on a bare PCB.
I found a single factory that makes all three, and they use what is the most common part numbering system (but not as common as the TF01 style numbering for flash card sockets)
@Jin /me signing up for a volounteer. If you could add a few (lets say 5) transistors to replace Q402 in one package that would be great. Cannot wait patiently enough😆
Really happy with this board, and the final version is killer. I’m going to read up on the chip and try to get a 2wire mode going. As I recall it has some odd number of bits during the initialization. RTS or something.
Received the socket samples. Pretty happy with these.
I got other samples from ShuoHan, who makes the Bus Pirate USB and buttons. They’re the spring loaded ejection type and I don’t like how they feel without an enclosure.
Bummer from the SIM socket people. They don’t want to sell less than a reel (1000? 3000?), and I doubt we sell 100 boards. They advertise singles, but they now say “sample only”. Maybe I can buy a 100 samples? They’re going to get back about possible distributors tomorrow.
I reworked the board a bit:
Added mini/micro/nano SIM sockets on the top side
Moved KF011C to bottom side
Reordered the pin connection to better suit the RP2040 PIO way of doing things
Bigger, clearer silk labels on the top.
ETA: I think this should probably have a “true” VCC and GND header as well.
ETA2: maybe an smd slide switch? With the labor to put headers on pins, I doubt it’s cheaper to use header than an actual slide switch.
I started the 2wire library for the SLE4442, but I also have some plain I2C memory cards (24C02, 24C16 eeproms). They should have address A0-A1 (and the next 6? pairs).
It doesn’t respond to address scan. I tried both cards on 2 different versions of the socket. All the connections probed for shorts/bad joints. Logic analyzer to check the waveform.
A few times I did successfully get an ACK to 0xa1, but I could never repeat it. Maybe a different problem.
The SOP version of this chip works great with the current firmware.
It is being powered by the VOUT/GROUND, not an IO pin.
I tried various manipulations of the VPP and RST pins without luck.
This parallax basic example is the only thing that came up in searches. It seems to use straight I2C with 0xA0/0xA1 address.
Things to try:
Add 0.1uF or more cap
solder pins directly on card to eliminate adapter board issues
Add 2K resistors for a stronger pullup and scope the results
They’ll sell us 200 MINIMUM! 