STM32F4DISCOVERY is evaluation board with 32 bit ARM microcontroller and I’m surprised what features it can offer for around 11 euros.
- STM32F407VGT6 32-bit ARM microcontroller @168 MHz with 1 MB Flash, 192 KB RAM.
- Hardware debugging(limited On-board ST-LINK) via USB
- USB OTG port for connecting mouses, keyboards, USB flash drives
- 3 axis digital accelerometer ±2g/±8g with programmable triggers
- Digital microphone
- DAC with microphone socket
- 4 user controllable LED’s
This is a very basic Atmega328 development kit It includes:
- Atmega 328 8 bit microcontroller with 20 MHz crystal resonator
- PCB board with place for external components
- Power circuit that allows powering Atmega directly(2.7-5.5 V), or through a L7805 voltage regulator(8-35 V). L7805 circuit includes a thermal fuse.
- 10 pin ISP connection for programming.
A kit comes as true kit, and components must be soldered by user.
This is a very simple capacity tester. It consists of single resistor that discharges battery. Arduino measures the voltage drop across resistor. According to Ohm’s Law current = voltage/resistance. Every second value of current is divided by 3600 and summed up to get the capacity expressed in Ah (Amp per hour).
I have used two parallel connected resistors that total resistance is 6.9 ohm. Make sure that they have proper power rating, if You don’t want them to convert to smoke. If voltage across 6.9 ohm resistor is 3.7 V, then current – 0.54 A, power ~ 2W.
SEN136B5B is a Ultra Sonic range measurement from SeedStudio. It can measure the distance by sending a 40k Hz ultra sound impulse via the transmitter and calculating time needed for echo to reach receiver. Detecting range: 3cm-4m. More information about device.
In the description of module is mentioned that it is compatible with Arduino library, but I decided to write program without using PulseIn command.
ADXL335 is 3 axis accelerometer with analog output from Analog Devices. You can buy it as an evaluation kit with standard 2,5 mm connector.
ADXL335 acceleration measurement range is +/- 3 g. Supply voltage is 1.8 - 3.6 V, however all specifications at the datasheet is given at 3.0 V. This accelerometer has 3 outputs for X,Y,Z axis which voltage is proportional to acceleration on specific axis.
At midpoint when acceleration is 0 g output is typically 1/2 of supply voltage. If a supply voltage is 3V, then output is 1.5 V. Output sensitivity typically is 300 mV/g.