The [BlueTooth RS232 adapter] converts an RS232 (serial) signal to a bluetooth radio link. Can replace an USB-RS232 cable although runtime logging is currently ~10 Hz (instead of 25Hz although theoretically it could be similar with BT as with native RS232 or USB-RS232)
- paired easily (after powering up BT module: since I didn't have +5V on DSUB9/9 I had to use an USB cable for power)
- the green-LED indication light inside the module could be more visible (only visible in dark, or my palm around the module)
- connected with [VemsDisplay]
- (using the 2013-08-20 release candidate) successfully connected with the Alcatel Android (4.3, which did not work earlier, even after android firmware upgrade)
- Selecting BT, and appropriate paired device in "Settings" it connected via BT
- connected a bit lasily, took appr 8sec with AIM and 10 sec without AIM (v3 fw=1.2.11), but it was stable.
- Tested a few cases (poweroff/poweron BT, V3, RS232 disconnects, etc...).
- I could not reproduce the situation when the BT module had to be poweroff/poweron before it can connect (this was reported for some of the newer modules from USA, which are theoretically exactly the same RN41 BT modules previosly purchased from EU).
- It works fine for most users, but there is still a highly mysterious case where it's not (and there were about a dozen cases with connection problems initially that cured - usually supply-connection or OS related. In a notable case -5V supplied via the USB connector killed 2 BT modules )
- In any case, if there is any connection issue, supply voltage must be verified, and BT modules paired and tested on PC too (not just android).
- The latest [vemsdisplay] is usually greatest (and supports direct serial port connection also, not just BT and wifi/TCP), but for some old androids (even 4.2.2 ?) some [older VemsDisplay-2014-03-06.apk] could be better (eg. if cannot connect with bluetooth, install that, but important: manually uninstall VemsDisplay APP in settings/App before installing old versions to clear settings. Similar might be useful when upgrading, but almost certainly when downgrading: the old will NOT be able to understand some settings from the new, and it might "stop").
OLD info, mostly OBSOLETE... for developers
RN41 Firmware 6.15 04/26/2013 enters cmd mode even if xxx$$$zzz => no 1sec silence before and after $$$
- [http://ww1.microchip.com/downloads/en/DeviceDoc/bluetooth_cr_UG-v1.0r.pdf
- p32: If the device sees any bytes before or after the $$$ characters in a 1 second window, the device does not enter command mode and these bytes are passed through => SIMPLY NOT TRUE
- luckily, with only 0-1msec interchar delay (in a bytestream) xaxxx$$$zz does not normally (ever?) enter cmd mode. But with 30 msec interchar delay, RN41 sometimes enters cmd mode when it should NOT.
- see p26, about ST,<value> command, tried several settings: ST,0 ST,9 ST,253 ST,254
- in any of these modes, always possible to enter CMD mode with $$$ via RS232 ("local")... Even if bluetooth connection is up, even after 5 minutes after powerup. Even if xxx$$$zzz (no 1 sec silence before $$$)
- with ST,254 local config should be disabled (it is NOT)
- with ST,0 local config should be disabled when BT is connected (it is NOT)
- always verified the ST,<value> setting with GT (before and after the test). Made the test with hard-powerdown, powerup (not just R,1 command)
Although it should be very rare, even if it's configured properly according to the datasheet (to make unintentional reconfiguration virtually impossible),
- if someone is extremely unlucky, the module might be reconfigured unintentionally (when ECU sends binary data).
- Not bricking the module but apparently stop relaying => "not working". Annoying.
- can be configured again, but baudrate should be known or guessed from 115200, 57600, ... down the usual baudrates parity:none but parity:even also cannot be ruled out,
The certification process force us to use a finished bluetooth module. The GlobalSat BTM001 looks like the primary candidate but it looks like a few of the module manufacturers use a common pinout and footprint. 
How is two modules paired? AT commands like I have seen elsewhere?
It looks like the module need 3.3v and has an onboard 1.8v regulator.
Panasonic BTZ4002 is also very interesting and it is much smaller, Texas has a module that is 1/4 of the panasonic module. but we have no info on availability for the these modules.
The panasonic module may be available as C-COM BTM-106 with a bluetooth stack.
http://focus.ti.com/pdfs/wtbu/TI_brf6100_6150.pdf
http://focus.ti.com/pdfs/wtbu/bluetoothtools_120402.pdf
http://focus.ti.com/pdfs/wtbu/bluetoothcmos_120402.pdf
BGB202 http://www.semiconductors.philips.com/acrobat/literature/9397/75011409.pdf
BGB203 http://www.semiconductors.philips.com/acrobat/literature/9397/75013343.pdf
BGB204 http://www.semiconductors.philips.com/acrobat/literature/9397/75013343.pdf
A snippet from a philips press release:
Philips' Bluetooth BGB203 (Flash version) SiP will be sampling in July 2004 and will be available in production quantities in Q4 2004. The BGB204 (ROM version), which is footprint-compatible with the BGB203, will be available in production quantities in Q1 2005.
From the same press release:
The BGB203 Bluetooth SiP integrates 268 kB of Flash memory, making it easy for customers to develop software for self-reliant products such as voice headsets, car kits and PC peripherals. The BGB204 is cost-optimized with a proven Bluetooth HCI software stack in on-chip ROM for hosted applications such as mobile phones and PDAs. A smooth and easy cost-reduction path from BGB203 Flash- to BGB204 ROM-based products is enabled by a patch RAM mechanism and compatible footprint.
A few of the available modules: http://www.vems.hu/files/JorgenKarlsson/JLEYSC1.pdf
Most of the modules need a firmware, Widcomm (now owned by Broadcomm) makes the firmwares for most of the modules. Some of the above modules has firmware loaded and is certified. Some will need a firmware and has to be certified.(Has to be found with a firmware already loaded.)
I got TDK blu2i devel kit in my hands, one bare module and one covered USB module but its the same inside. These are class 1 devices upto 100m, a bit expensive but if you have bluetooth at your laptop then you just need one. Or any USB/rs232 bluetooth works fine at computer side. (of course if it's class 2 then range is only 10m..)
I made adapter between serial module connected to devel kit, it's two D9 connectors, 2-3, 3-2, 5-5 and at devel kit side looped 7 to 8. Yes, devel kit board have RS232 chip in it making it 'real' RS232.
Speed is by default 9600, but it could be changed. I haven't tested this in real action, only at my table. This is my first time with bluetooth so USE AT YOUR OWN RISK! :)
Serial device (slave) connected to vems have to be configured by connecting module to serial port and at terminal program (9600):
- at&f* - clear S registers to defaults
- at&f - clear nonvolatile memory
- ats512=3 - make device non-discoverable by other
- ats0=-1 - answer on ring, -1 means that RING etc messages are not shown
- at&w - save these settings to nv-memory
- at+btr000000000000 - add master (computer side) device to the trusted list. It is saved into nv-mem without at&w. (replace with real addr :)
- at+btr? - you can see the list of trusted devices if you want
Now connect this module to vems.
Linux with USB bluetooth module:
- Compile & install bluez-utils and bluez-libs
- modprobe bluetooth
- modprobe l2cap
- modprobe hci_usb
- hciconfig hci0 inq - to see bluetooth addr of usb device
- mknod /dev/rfcomm0 c 216 0 - also change priviledges
- rfcomm bind 0 00:00:00:00:00:00 1 - addr of slave device (vems side)
Thats it! Now megatunix using /dev/rfcomm0 or minicom also using /dev/rfcomm0
I'm not really sure are these AT-commands some kind standard. I have also BTM001 modules in my hand, but I haven't got it work at all! Maybe it have to be configured via SPI or something, BUT I HAVEN'T FOUND A GOOD DOCUMENTS OF IT! So if you know something about these crap BTM001, please tell it!
Actually this BTM001 is VERY similar to blu2i, same components at the same place, blu2i board is just bigger with antenna in pcb. Maybe it would work same way, but in class 2 (range 10m).