FAQ
What support materials are provided? This pi-school website will supplies support materials for  Case4-Kits and HapPi-Robots   The focus will be on educational using ScratchGPIO to start with and later on Python. Note The Raspberry Pi is an Open Source product so there are lots of other freely available examples available on the internet. What motors can I use with the HapPi add-on? Electric Motors (dc type) connected to motor 1 and motor 2 on the HapPi add-on connectors.  The common 6V to 9V motors  are ideal as low cost dc motors including  Lego® motors. Note - If using a 6 volt battery to power a 9volt motor it will not turn as fast as it would with a 9volt  battery. Motors rated at 2 to 4volts could burn out or run too fast  when run on a higher voltage than it was designed for. What H-Bridge chip is used? The HapPi add-on uses a SN754410NE H-Bridge motor driver chip.  The specification sheet says you can power it using 4.5volts to 36volts and up to 1 amp amp per channel. There are 4 channels so you can power four dc motors. For robots requiring both forwards and backwards movement only two motors can be connected.  You can control speed of motors  using PWM method (Pulsed Width Modulation)    See Texas instuments spec sheet for more details  http://www.ti.com/product/SN754410/description What batteries can be used to drive the motors? Supplied is a 6volt battery holder to hold  4 x AAA  batteries. This is used to drive the motors only (not the Raspberry Pi as well). See chip specification  above for more detail.
Power for the Raspberry Pi? The Raspberry Pi  works in a narrow voltage range from about 4.8 volts to 5.2volts.  This is not  good news for robot builders as batteries loose voltage as they run down. A good way to get a reliable 5V supply is to use an approved Raspberry Pi USB Hub but only if you can live with umbilical wires dragging behind. For free roaming autonomous mobile robots  a portable power supply is required such as a Power Bank used to recharge phones but needs to have at least 2amp rating.  (best prices are available and are aimed at phone users wanting an emergency recharge. (check the specification carefully when buying to ensure they come with a micro-USB lead most do). Most problems beginners have is due to having a poor voltage supply, especially when extras are added such as  aWiFi dongle that also requires power. Good news is that the Raspberry Pi version B+ has better voltage control then earlier versions. For more help see page covering this topic in more detail. How tough are the HapPi kits? To help answer this we videoed a  drop test, http://youtu.be/i1bGdCIgzas which shows a Raspberry Pi in a Case4-Pi being dropped from 3metres onto a concrete floor with no resulting damage. The SuperSheet card, patent pending, is a multi-layered rigid flat sheet about 1.8mm thick, with various potential hinged aperture openings (’push out holes’) with an  protective glossy surface layer that also acts as the hinge when folded and to make 3D forms. It is suitable for indoor use and can be easily modified if necessary.  When folded it becomes a surprisingly strong rigid form.  The big advantages being - Models are low cost, attractive, rigid, lightweight, quick assembly, easy to modify  but it would not withstand being stood on. 
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