Using a Duemilanove as USB<->TTL Converter

Submitted bypatrik onTue, 2012-08-21 13:12

The Duemilanove and likes has hardware to connect the Arduino to the PC:s USB-port. When you build a clone you usually dont add hardware for this. Instead one might use a FTDI-cable, or why not a Duemilanove? I have one for prototype building, and it can be used for programming the clones to.
-Remove the Atmega from the Duemilanove.
-Connect the Duemilanove to the clone:
Duemilanove <-> Atmega based clone:

Reset -> reset(pin 1)
5V -> Vcc(pin7,20)
Gnd -> GND(pin 8,22)
RX -> RXD(pin 2)
TX -> TXD(pin 3)

Then just program the clone as usual.

Saab 9-5 handbrake adjustment

Submitted bypatrik onWed, 2012-06-06 11:22

In short: Lift the car, remove the rear wheels. Adjust til the wheel is locked, loosen the adjuster until the wheel moves freely. But not too much!
Good link:

The adjuster is reached with a flat screwdriver through a hole in the brake disc. It's hard to see, but theese pictures of how it looks with the disc removed can help.

Arduino and the HH10D humidity sensor

Submitted bypatrik onTue, 2011-03-08 09:42

The HH10D is a relatively cheap humidity sensor that can be bought from Sparkfun. It has a capacity sensor on board, which is connected to a 555-based frequency generator. Thus the device gives a frequency out that depends on the humidity in the air. But this is not all. The device also has an I2C Eeprom, where a calibration value is stored. This is programmed at the factory, and only has to be read once. When you have the value, it can be hardcoded in the Arduino code (and put on a sticker on the HH10D).


Submitted bypatrik onMon, 2011-03-07 10:00

Wired node #2. Mounted inside, measures values, collects data, displays data.

-Atmega 168.
-MAX485 RS485 transceiver.
-433 MHz rf receiver.
-MPXA4115A air pressure sensor.

MCP9701A temperature sensor
A simple temperature sensor from Microchip. Gives out 19.5mV/degree celsius, at 0C the output is 400mV. Connected to a analog input on the Atmega.
For accuracy it has to be calibrated. I used a small can filled with snow/ice that had just melted. The output of the MCP9701 was then measures, in this case it gave xx volt.


Submitted bypatrik onTue, 2011-02-22 21:21

This project's goal is to collect data from the surroundings

The device uses different sensor nodes. Some of them are connected via RS485, some are wireless. The wireless sensor are used for temperature and humidity. The wireless devices are not homebuilt, they are cheap extra devices for a commercial weather station (From Esic, Clas Ohlson item number 36-1797).
In the network there is also a number of wired devices. They connect via RS485, and to a PC via a RS485/RS232 adapter. For simplicity, these devices are built like Atmega168-based Arduino-clones.

Buildning a small Arduino clone

Submitted bypatrik onMon, 2011-02-14 15:57

Here I will build a really small Arduino clone. A MCU a Atmega168 is used. To save space and solder the device is preloaded with the Arduino bootloader, before the other components are mounted.

1 - Program the bootloader.

-The Mega168 is placed in the socket on a Arduino Duemilanove, replacing the original Mega328.

-An Avrisp mkII programmer is attached to the programming header on the Duemilanove, to this card I also connect an external power supply.

-Windows XP is booted in Virtualbox on my Ubuntu system.