exhi:bit Pedestrian Crossing experiment board
Friday, 23 December 2016 | John
I have previously reviewed Proto-Pic's exhi:bit Prototyping System for the BBC micro:bit to which I awarded 5 stars. Shortly after receiving this the first of the new exhi:bit Pedestrian Crossing experiment boards were made available on their website. This is a purpose made printed circuit board to enable its users to write programs to replicate the sequence of events of a real Pedestrian Crossing. The board is designed to plug into the pair of ten terminals at either side of the exhi:bit prototyping system and also the four 5 volt and Ground supply terminals adjacent to the micro:bit's main socket. With 50 years of soldering experience behind me it was a straightforward exercise to assemble the board but it is also available preassembled for a very moderate extra charge if required. I would add though that if you are not very experienced with a soldering iron you should follow the excellent video tutorial on assembling this board on their website, found within the Pedestrian Crossing listing and also on the YouTube tab at the top of the page.
Some readers of this review may have noticed that it has been resubmitted at my request. In the previous version I must have had a 'senior moment' when, in the third paragraph, I mentioned that two of the components on the board were not accessible from Microsoft's Block Editor. In fact I contradicted myself in two consecutive sentences regarding Pin 16 of the BBC micro:bit. On board there are 10mm Red, Amber and Green LEDs to represent the traffic lights, a further two 10mm Red and Green LEDs to indicate the little red and green men. Beneath the latter there is a Wait Button, a 3mm Yellow LED indicator and at the bottom there is a small circular Buzzer to replicate the 'beeps' that sound when it is safe to cross. The pins to which these components are linked to on the BBC micro:bit are also clearly marked and, as in the prototyping board, there is no need to have a drawing of these connections nearby to be able to program the sequence.
I have downloaded Proto-Pic's Micro Python example from the link on their website within this product's information and it runs the lights and button sequence as in a real crossing. I then attempted to program the sequence using the Microsoft Block Editor from the micro:bit.org website and found that only six of the data pins could be written to, Pins 0, 1, 2, 8, 12 and 16. There is a component on the Pedestrian Crossing experiment board that is also connected to the micro:bit's Pin13 which is the Wait LED. This is no problem at all when using Micro Python but there would appear to be a snag when using the basic Microsoft Block Editor, Pin 13 is not accessible from this basic editor. Although I had not had a close look at it before I then tried using the Microsoft PXT (Beta) Block Editor from the same micro:bit.org website and, lo and behold, all digital pins are available in this package. Being a seasoned user of the original Block Editor I was very quickly able to put together a sequence of blocks to replicate the events of a Pedestrian Crossing. I assume that this Beta version of the Block Editor will eventually replace the original one. So far I have found no problems when using this Beta version, it has many extra and useful blocks which are equally suitable for more advanced users and they certainly work very well with Proto-Pic's exhi:bit Pedestrian Crossing experiment board.
What I was trying to highlight in the original review is that every data pin on the micro:bit is accessible when using the more advanced Microsoft PXT (Beta) Block Editor. My humble apologies if this caused any confusion, I am keen that the Pedestrian Crossing experiment board is seen as an excellent platform to program and demonstrate the light sequence along with the generated tones triggered with the button on the board. Everyone that has seen it working have been very impressed with this board and its educational value.
Another winner from Proto-Pic and I had a lot of fun using it with my 5 and 6 year old 'techie' grandsons during the Christmas holiday period.
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