PICAXE

Abstract: As the prices of commercially available electronic and mechanical components decrease, manufacturers such as Devantech and Revolution Education have made encoded motor controller systems and microcontrollers very accessible to engineers and designers. This has made it possible to design sophisticated robotic and mechatronic systems very rapidly and at relatively low cost. A recent project in the Autonomous Systems Lab at Middlesex University, UK was to design and build a small, automated, robotic bartender based around the 5 litre Heineken 'Draughtkeg' system, which is capable of patrolling a bar and dispensing beer when signalled to by a customer. Because the system was designed as a commercial product, design constraints focused on keeping the build cost down, and so electronic components were sourced from outside companies and interfaced with a bespoke chassis and custom mechanical parts designed and manufactured on site at the University. All the programming was conducted using the proprietary BASIC language, which is freely available from the PicAXE supplier at no cost. This paper will discuss the restrictions involved in building a robot chassis around 'off-theshelf' components, and the issues arising from making the human-machine interaction intuitive whilst only using low-cost ultrasonic sensors. Programming issues will also be discussed, such as the control of accuracy when interfacing a PicAXE microcontroller with a Devantech MD25 Motor Controller board. Public live testing of the system was conducted at the Kinetica Art Fair 2010 event in London and has since been picked up by websites such as Engadget.com and many others. Feedback on the system will be described, as well as the refinements made as a result of these tests.

Abstract: Juxtacellular neuronal labelling is a method which allows neurophysiologists to fill physiologically-identified neurons with small positively-charged marker molecules. Labelled neurons are identified by histochemical processing of brain sections along with immunohistochemical identification of neuropeptides, neurotransmitters, neurotransmitter transporters or biosynthetic enzymes. A microcontroller-based pulser circuit and associated BASIC software script is described for incorporation into the design of a commercially-available intracellular electrometer for use in juxtacellular neuronal labelling. Printed circuit board construction has been used for reliability and reproducibility. The current design obviates the need for a separate digital pulse source and simplifies the juxtacellular neuronal labelling procedure.

Abstract: Single chip computer systems started with the Basic Stamp computer system that solders computer parts into a printed circuit board, the size of a large Integrated Circuit (PICAXE). Now, true single-ICs, as small as 8-pin in sizes, can become a complete computer system with all hardware and operating system. These are the PICAXE systems based on the Microlab PIC microcontrollers. A sample datalogger design, with its Basic source code is provided in the Proteus Professional software, and this circuit is simplified so as to use the least component and source code. It is used as the basis to test a simple application where temperatures are taken at a regular interval and stored in the non-volatile EEPROM memory. 181 bytes out of 256 of the EEPROM is used up by the Basic program loaded into the PICAXE-08M, the smallest PICAXE with 8 pins. The 40-pin PICAXE40X2 has 4096 bytes of EEPROM. As a computer system, users can communicate with the PICAXE IC using a serial port, and these serial ports can be linked to other devices, such as serial EEPROM or other computers, using the I2C protocols for large networks. The networks can be linked wirelessly but the simpler serial protocol, the RS232, will be the default for bootstrapping and communication. The cost of these computer systems is less than RM30 each so it could be cheaper and more effective to just produce lots of them and collect their data to be downloaded to a central server. This paper reviews PICAXE systems for their suitability to log temperatures of outdoor cabinets of Telekom Malaysia.