Hi, i have trouble connecting my selfmade Bluetooth module to the Bot Board.
Its a copy of this sketch:
plischka.at/images/Basisboard%20 … %20Sch.png
I connected it to SSC-32 (at the 3pin jumper) and it works very good, but i cant get a connection with BB. To connect it i used Pin 2, 3 and 5 of the DB-9 connector and the 5V i 've got from the middle of one 3pin jumper.
Serial setup is 38400bd, 81N.
Any Ideas?
Regards
Stefan
Hi Stefan,
Others with more electrical savvy can answer this better, but my guess is that it has to do with voltage levels. You say you can hook it up to the SSC-32 at the 3 pin connection. This connection works on TTL voltage levels (0 and +5v). Whereas if you are connecting to the DB9 pins of the BB2 (or SSC-32), they are expecting RS232 level signals, which have a different range (en.wikipedia.org/wiki/RS-232#Voltage_levels)
Kurt
Hi Kurt,
yes, i thought about that point.
The SSC-32 has a RS232/TTL converter onboard so i used the 3pin connector where the TTL Level is to be found.
Because the BB has no converter at all (i havent found one) i thought that using TTL level would be the right choice.
Is it sure that there must be true RS232 level at the DB9 port? Is there any Datasheet available?
Regards
Stefan
I believe that it is not the BB2 that does the level conversion, but the actual processor (such as the Basic Atom Pro 28) plugged into the board. More details about the chip can be found on it’s data sheet: downloads.basicmicro.com/downloa … _B0204.pdf
Kurt
Ah, ok, now i understand.
Because there are no level shifters or something like that on the Bot Board and schematics there must be all the level shifting in the Atom processor itself.
Thanks a lot.
Sorry for the silly questions, i am more familiar to RC submarines and quadrokopters. Robotics is completely new to me.
Yes, the BBII does the level conversion on the Basic Atom Pro 28 chip with a couple of transistors and resistors.
Curious why you used Schmitt trigger parts on your board, also, connections to the LM1117 look a little funny on the schematic, I assume you’ve wired it OK.
Alan KM6VV
Yes, its definitely wired ok. Its works with SSC-32 and the bluetoothboard works with my quadrokopter.
The Schmitt Triggers are used as level shifters because the bluetooth module works with 3,3V.
What looks funny with the LM1117? I cant see anything strange.
Two pins out of LM1117? You’re not connected to the out. Just a drawing.
the 74HCT parts are not level converters themselves, and you don’t need the Schmitt Trigger (hysteresis) property, just the buffering. the associated R1/R2 parts actually change the level.
Not a problem, just thought I’d ask/mention.
Alan KM6VV
Level conversion is accomplished on the BasicAtom28B chip with the XN04211 transistor pair, along with a BC857B transistor, a 1n4148 diode, a few resistors and a cap.
That was the question, wasn’t it?
Alan KM6VV
I dont care about the LM1117. Its got three legs, not enough room to make mistakes 
BTW, in Kurts basicmicro link is a schematic of a USB/RS232 converter which will be plugged into the DB9 connector. The FTDI chip doesnt have level shifting but a ATN wire.
I will try to pull the pin 4 of the DB9 up to 5V and see what happens
the ATN line connects to one of the RS-232 handshake lines (DTR) to allow programming.
Alan KM6VV
Hm, doesnt work. I switched RX and TX, but no luck.
I think i have to check out the XBee section.
Thanks for your help
