Bluetooth module access to RX0/TX0

Combining the power of the ATmega2560 MCU with onboard Ethernet, a microSD card slot, an efficient switchmode power supply, and a small prototyping area. [Product page]
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Joined: Tue May 22, 2012 8:47 am

Bluetooth module access to RX0/TX0

Post by philgaskin » Thu Dec 27, 2012 12:26 am

I have built a complete garden automation system using the fantastic Ethermega. The project has slowly evolved to control lawn sprinkers, pump and flood lighting as well as measuring the water depth in my well and intercepting the 433MHz weather info transmitted by my weather station. I am also using a realtime clock module and pushing weather and sensor data into MySQL on my server. Basically I can't believe how versatile the ethermega is!
I am however getting frustrated at having to visit my garage to plug my laptop into the ethermega to upload tweaks to the code (it gets cold in the UK).
I have been investigating buying a cheap bluetooth module connecting it to RX0/TX0/Reset to enable me to program the ethermega from the comfort (and warmth) of my house.
Obviously for me to program the ethermega via bluetooth, I need to access the TX0/RX0 pins; however I am a little nervous of simply wiring the pins on a bluetooth module to the RX0/TX0 pins on the ethermega as I don't want to create a short between the USB module on the ethermega and the bluetooth module.
I reviewed a similar topic viewtopic.php?f=25&t=107 and it appears that the ethermega does have protection resistors between the USB controller and the ethermega itself, but as I intend to leave the bluetooth module powered all of the time (with no USB connection to the ethermega) I just want some confirmation.
Can anyone confirm whether I can access the default RX/TX pins without any damage? I don't want to destroy all all of the time I have invested in my project.
If anyone has any experience of using bluetooth in this way I would also be interested in circuit info.


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