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| arduino:metp0000_driver_library [2023/03/12 09:01] – [METP0000 Library] tony | arduino:metp0000_driver_library [2026/09/06 02:37] (current) – external edit 127.0.0.1 |
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| As mentioned earlier the library is based on a standard Arduino LiquidCrystal.cpp LCD library. I wrote a version (v1.30) with a "write()" function suitable for use with the standard <print.h> routines. This worked fine, but didn't allow for controlling the decimal point - it was unable to set the decimal point as part of a digit. Instead it had to display a blank digit with a decimal point set in the corner. Besides looking strange, that wasted a whole digit space just to display a decimal point, and we don't have a lot of digits to play with. | As mentioned earlier the library is based on a standard Arduino LiquidCrystal.cpp LCD library. I wrote a version (v1.30) with a "write()" function suitable for use with the standard <print.h> routines. This worked fine, but didn't allow for controlling the decimal point - it was unable to set the decimal point as part of a digit. Instead it had to display a blank digit with a decimal point set in the corner. Besides looking strange, that wasted a whole digit space just to display a decimal point, and we don't have a lot of digits to play with. |
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| ==== Character Set ==== | ==== Character set ==== |
| Because driving the 9 segments necessitates bypassing the 7 segment decoder, we are free to create whatever character shapes we wish out of the available segments. To simplify development I used a 16bit word to define each character - 3 nybbles containing 3bits each, plus a fourth nybble that I occasionally used to specify the digit position (as not all digit positions are exactly the same). If I continue to develop this driver, I might truncate this to 8bits per digit, and handle the single bits for the decimal point or comma separately. I initially hand crafted a table of 9-bit alpha-numeric character patterns based on other peoples 7-segment character fonts. I then came across Jose Pino's XLS spreadsheet ((http://www.josepino.com/microcontroller/7-segment-ascii)), which I modified for the 9 segments and odd coding required for this display. In my version the results are shown as a 3 digit number suitable to use as the hex character definition in my driver.\\ | Because driving the 9 segments necessitates bypassing the 7 segment decoder, we are free to create whatever character shapes we wish out of the available segments. To simplify development I used a 16bit word to define each character - 3 nybbles containing 3bits each, plus a fourth nybble that I occasionally used to specify the digit position (as not all digit positions are exactly the same). If I continue to develop this driver, I might truncate this to 8bits per digit, and handle the single bits for the decimal point or comma separately. I initially hand crafted a table of 9-bit alpha-numeric character patterns based on other peoples 7-segment character fonts. I then came across Jose Pino's XLS spreadsheet ((http://www.josepino.com/microcontroller/7-segment-ascii)), which I modified for the 9 segments and odd coding required for this display. In my version the results are shown as a 3 digit number suitable to use as the hex character definition in my driver.\\ |
| {{ :arduino:metp0000:metp0000 character_set.png?600 |7 Segment character set v1.1.}} | {{ :arduino:metp0000:metp0000 character_set.png?600 |7 Segment character set v1.1.}} |
| Overall I'm not convinced by the results, so still a work in progress. | Overall I'm not convinced by the results, so still a work in progress. |
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| ==== μPD7225 command set ==== | ==== μPD7225 command set ==== |
| * MODE SET | * MODE SET |
| * initialise the controller | * initialise the controller |
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