RN-41 Module not responding

Wireless & IoT
1

I recently got an RN-41 module from sparkfun, and am having trouble getting it to do anything.

From the user guide, it appears I can simply connect it to a power supply (3.3V) and it will appear as discoverable by other bluetooth devices. However, it does not appear in my “bluetooth neighbourhood” or any other listings I can get under windows XP (I’m using a Belkin F8T013 USB adapter).

I’ve also tried connecting it to a serial interface, but don’t get any reply from the module (yes, I’ve set it to 115200 - N - 1).

At the bottom of the user guide it mentions that one of the hardware failure indications is a short between GND and Vcc. I get ~1k between those pins so I don’t believe this is the case, plus, I’m not using any of the IO pins (yet). I’ve had one of these modules working in the past, so this is baffling.

Does anyone out there have any ideas as to what this problem could be? What’s the chance the module is DOA?

Thanks, philip.

2

I just happened to test a couple of these modules out this week. You should only need 3.3V on pin 11 and ground on pin 12 to get it to function. 1K of resistance between VCC and ground seems kind of low. I get approximately 16K. Also, the serial interface is TTL level. So, make sure you have a RS232 driver IC if you are connecting to a PC. If you connect a LED and 220 ohm resistor between pin 21 and VCC, you should see the LED flashing.

3

I’m using an FT232R chip for USB/UART conversion, which is 3.3V on Tx and Rx. I attached an LED where you mentioned, and it doesn’t flash. Combined with the low resistance, I’d say the module is probably dead. :frowning:

Thanks for the reply anyway.

4

I had another thought. I ran into a problem when I used their reference design schematic. If you use a MCP810 for the reset line, it won’t work. The reset is a low active signal. So, you either need to leave the reset disconnected or use a MCP809 reset IC.