The Simpad SL4 has an unused serial port on its main board - that's the little white rectangle in the upper right corner.
The Simpad SL4 has an unused serial port on its main board - that's the
little white rectangle in the upper right corner.
The port was designed to connect a DECT module, which I do not have.
However, it is just a standard serial port - we can use it to connect
anything that can talk to a serial port. So I started wondering
something like one year ago: "what about a bluetooth chip ?"
I did some research, and failed. I could not initially find neither a
bluetooth module nor any way to connect it to the simpad. I tried to set
up a group order for bluetooth chips, but the company which was
approached and initially interested just stopped anwering emails.
I was then given by someone who had tried to do the same hack on its
simpad a Siemo S50037 Bluetooth Module,
based on a CSR Bluecore 01. This is a "one chip" solution: you basically
have everything you need in it. Just make a serial connection and you
are ready to go !
However, I still could not find a good way to connect to the motherboard, I could do some direct soldering, but that involved spending a lot of time with a multimeter trying to figure out which pin where accessibles from some parts of the motherboard, at the risk of frying something in the process or during soldering. So I decided to wait a little bit and try again later.
Some months later, I resumed "from scratch" after beecon.de reported
success doing such a bluetooth module using the DECT port. My first
problem was to find a suitable cable and connector to fit in. While it
was not a serious problem, I wanted a beautiful hack since it would
definitely not be the "first" simpad to get bluetooth.
However, it did involve soldering directly to the motherboard, which I
though was not elegant. Hey - somebody had it already working, so what's
the point in doing the same thing? The goal was then set to do a
"beautiful hack". As you can see, Beecon prototype is soldered to the
motherboard - that's also taking the risk of frying it it something fail
(say if by mistake you short important connection and can't unsolder them)
After some serious googling during a week with various keywords in german and in english, I could finally find a shop that was selling MD35 DECT modules - the same one used inside the Simpad SLC. I contacted the shop and quickly figured out with them that the connector was the same I had - 20 pin, with a 0.5 mm pitch.
I temptatively order 2 connectors and 2 "fpc" flat cables. When I received them, I immediately tested them - they perfectly matched the Simpad connector ! Cost : around 20 euros.
The next problem was connecting that to the Siemo S50037. While I know soldering, the contacts where far too tiny, and I didn't have any of the required material. A local shop got me everything I needed.
The most difficult to find would certainly have been a integrated circuit board. However I was pretty lucky- the shop had several units "unclaimed" by clients, and tried to find one where the pitch of the FPC connector and the circuits would match.
That alone saved hours and money. It was then easy to solder the connectors and some pins, using special "stripping" wire (very thin) and very thin soldering which where purchased at the same shop.
However, since I had some other work, and very little time on my hand (I had already spent hours on this hobby project :-) I decided to let them do all the drilling, soldering and stuff, based on some personal notes. Cost: 70 euros.
I just soldered a couple of cables to the Siemo I had forgotten on my notes, and then did the first attempts to create a working module, deciding which wire from the serial port went to which wire on the bluetooth module. I was helped by Opensimpad references, even though it was partially wrong (20 pins vs 22).
Then started some hacking. Nothing did reply to my various communications
attempts with pskey. I quickly realised I was not drawing enough
power from PIN #5 (power) controlled by CS3. I decided to draw power
simply from the 5V on PIN #20 & #19.
I then tried to connect a multimeter to the serial port - I realised I
had mistakenly connected the FPC cable upside down !
Trying again, I now had power on the VREG pin on the Siemo. That was a good start. I then monitored again the serial port while transmitting data - I definitively saw something. Yet I tried everything but could not talk to the Siemo module. When using a special loose wire to initiate an undocumented function that's broadcasting the Siemo name to every Bluetooth device currently scanning, I finally saw the module.
But I could not l2ping it or connect to it in any way. So I think the module is working, but it may be missing a firmware. Currently the hack is stopped until I get either get another bluetooth module or figure out what's wrong with that one, with a SPI cable and some software to put a new firmware on the Siemo.
I spent around 100 euro, but I had hours of fun and learnt a lot about
Simpad hardware and bluetooth in the process. While I'm definitively not
an hardware guy, designing and soldering was quite fun !
If you want to try something like that, I suggest you sign up on csr.com
website - there's a lot of documentation about CSR bluecore chips. If
like me you do misconfigure your PSKEYS, your chip will be rendered
useless. So please read a little
explaination about BCSP before using pskey.
Do *not* change the default speed unless you have to, since hciattach
*can* change the speed. You should put a safe value such as 115 200. I
did put 230 400 to experiment hardware speed limits (it works fine in
BCSP !) but please don't do this.
As you can see, we are going to reconfigure the GPIO and map them to a usefull SPI connection to the MMC card (BTW I refer to SD as SD/MMC since we are going to access them in MMC compatibility mode). An excellent explaination about SPI is available on www.cc5x.de/MMC.
| Function | PIN # | Original direction | GPIO # | SPI function | New direction |
| -------- | ----- | ------------------ | ------ | ------------ | ------------- |
| DCD | PIN 08 | (in) | GPIO 23 | DO | (in) |
| DTR | PIN 11 | (out) | GPIO 07 | CS | (out) |
| RI | PIN 14 | (in) | GPIO 19 | CLK | (out) |
| DSR | PIN 16 | (in) | GPIO 06 | DI | (out) |
Note: I ordered a connector from www.jelu.se which I intend to use "in
the future" i.e. when I have some free time.
After soldering it, here are the results :
As you can see, the SD/MMC + Bluetooth module is quite big.
However, it fits fine inside the Simpad. In fact, the biggest part is
the pins I use to solder the 2nd serial port wires to respectively the
Bluetooth and the MMC.
Hopefully when I receive the SD/MMC connector, I will be able to pierce
a nice opening in the Simpad plastic and solder the connector to the
mainboard. The end result will be awesome!
If you want to do similar hacks, there are 2 spare GPIOs inside the
Simpad : if you remove the SmartCard controller you get GP10 which is
pin40 of the TDA8007 controller. Since the
SmartCard drivers are not ready yet, it won't be a big loss.
The other GPIO that could be used is GP21: it is on pin 5 of the unused
real time clock U35 (I was told the SA1100 internal RTC is used
instead). It's not easy to find - look for the TLC7733 chips which are
above and left (U16 U8 and U22).
Next hack:
Fitting in a GSM module, to make the Simpad a big cellphone.
This will certainly require the first serial port. Since I'm only using
it for flashing and minicom, this is not very important. I'm sure I
could put a switch somewhere to power on the GSM module on toggle
between external serial port and internal GSM module.
Any help is welcome
from fellow simpad owners with JTAG/NOR flash/ARM knowledge!