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MSP430G2452 acting as a TMS0803 calculator chip. Emulates TI Datamath 2500 and Sinclair Scientific. There seems to be some interest in building this emulating calculator so I will start a build thread. /EDIT add youtube video, different versions of PCBs, try to get everything in one place. 1st July. 2014 /EDIT add build tips down under, here 8th July, 2014 I got introduced to a web based calculator emulation via this thread. I got interested and start playing w/ the idea of implementing the emulation on an msp430, my code is based on Mr Ken Shirriff's work from the following pages. TI DataMath 2500II/1500? emulations Sinclair Scientific emulation Eventually I built the emulator on a standalone PCB design fitted w/ bubble leds from the '70 when the original calculators were made. /EDIT add version 0, version 1 photos This is the original failed build (w/ faulty 9 digit leds) and the 1st successful build. Next are the 1st two I built. They were given away a few weeks ago. Here is a close-up photo. Eventually I build 3 of these and they are all gone. /EDIT add version 2 photos I did a revised PCB to layout the buttons for better ergonomics, also adding a bypass cap and programming "loops" for in-circuit programming. I had proof-build one (from resurrected parts) and am waiting parts for a few more. There is another thread in this forum for a good build / buy. I am posting the bits that's needed for whoever interested to build it. This is all that's there 1 MSP430G2452, from your Launchpad G2 (the "other" chip in the package) 2 bubble led, from sparkfun ($2.95 ea) 20 tactile buttons, 6 x 3 x 4.3mm, from DX ($4.76/100) 1 spdt dip size switch, from DX ($7.37/100) 1 CR2032 cell holder, from DX ($3.14/20) 1 miniature red led thru-hole, forgot where I got it (see picture) 1 47k pull-up resistor * The miniature red led is to show the "negative" sign. The original calculators have 9 digit displays, since we have only 8 digit, I used a led to show the negative sign when needed. * You can try different CR2032 cell holders, or even paper-clip diys, the pcb make provisions to mount different cell holders. I am attaching the schematic here but it is not very readable, I started my pcb design by placing components 1st, make traces. And lastly I let Fritzing to auto route the schematic. It is easier to understand the connections w/ the ascii art schematic, in my opinion /EDIT corrected minus sign led, should be on P1. MSP430G2452 ----------------- /|\| | | | | --|RST | | | 2 x 4 digit bubble led | digit 0 P2.0|----- +---------+ +---------+ | digit 1 P2.6|----- | % % % % | | % % % % | | digit 2 P2.1|----- +---------+ +---------+ | digit 3 P2.2|--/ | digit 4 P2.3|--/ | digit 5 P2.7|--/ | digit 6 P2.4|--/ | digit 7 P2.5|--/ segment a to g + dot........ | | / ....\ | | / \ (led for minus sign) | segment A P1.2|-----+-----+-----+-----+-----+-----+-----+-----+----(|<)-+ | | _=_ | _=_ | _=_ | _=_ | _=_ | _=_ | _=_ | _=_ | | | segment B P1.3|-o o-+-o o-+-o o-+-o o-+-o o-+-o o-+-o o-+-o o-+---------+ | | _=_ | _=_ | _=_ | _=_ | _=_ | _=_ | _=_ | | segment c P1.7|-o o-+-o o-+-o o-+-o o-+-o o-+-o o-+-o o-+ | | _=_ | _=_ | _=_ | _=_ | _=_ | _=_ | | segment D P1.1|-o o-+-o o-+-o o-+-o o-+-o o-+-o o-+ | | _=_ | _=_ | _=_ | _=_ | _=_ | | segment E P1.5|-o o-+-o o-+-o o-+-o o-+-o o-+ | | _=_ | _=_ | _=_ | _=_ | | segment F P1.4|-o o-+-o o-+-o o-+-o o-+ | | _=_ | _=_ | _=_ | | segment G P1.0|-o o-+-o o-+-o o-+ | | _=_ | | segment H P1.6|-o o-+ (not all buttons populated) | | The source code is in github There is also good amount of H/W information commented inside the code If you plan to design your own PCB, the basic principle in relationship w/ the code is P1 for LED segments P2 for LED digits P1 also for key button scanning You can move things around as long as you observe the above. I.e. If it fits better on your PCB, you could swap digit 1 w/ digit 3, segment A w/ segment E, etc, etc. All you need is to change #define in a header file and compile. I will post the PCB separately. Also working on a better design and will post it also.