![]() ![]() The dictionary definitions are stored locally, and because it's ad-free there's no need for a network connection. Dictionary is ideal for both native English speakers and English learners or people studying the English language. One of them (the master) reads the keyboard matrix, updates the LCD.Dictionary is a free offline English dictionary containing over 200,000 words and definitions and no ads. My design uses two MSP430G2553s connected to each other over UART. The interface code also added a lot more to the size than I expected but I was able to add checks for most of the functions and add some meaningful error messages. Part of this is due to all of the functions used to access external memory. In the end it grew bigger than this and I had to use two MSP430s to hold everything. ![]() When I began this project I wasn't sure how much I could fit into 16kB of firmware space. The settings page also shows the current battery charge. After setting the accuracy, the program finds the largest element in the CORDIC table that is still significant, so that no time is wasted on elements that have no effect on the answer. With 32 decimal places calculations take 3-4 seconds. With the default of 12, trig functions calculate in about a second. The settings page allows the accuracy to be set from 6 to 32 decimal places. After setting accuracy to 24 places arcsin(arccos(arctan(tan(cos(sin(9)))))) evaluates to this: One way to measure the accuracy of calculations is with the calculator forensic found here. I was able to speed the shifting up even more by using another lookup table that let me right shift 4 digits at a time. Instead, a lookup table is used with adds and shifts, which are much faster. This is a very efficient way to compute these functions for processors that cannot multiply or divide quickly. ![]() Before processing void puts ( unsigned char *msg)The trig and log functions are computed using CORDIC routines. These are usually ignored by the compiler if they are not recognized, so they are a convenient way to communicate with the preprocessor. To mark variables as external, #pragma directives are used. External variables are all stored as pointers, so the PC version will work exactly the same with or without the preprocessor. A simple equation like: X+=Y*Z-Q would become something like this (assuming we are passing pointers): RAM_Write(X,RAM_Read(X)+(RAM_Read(Y)*RAM_Read(Z)-RAM_Read(Q)) To simplify things, I wrote a preprocessor program that looks for any variables that need to be stored in external RAM and converts access to them to function calls. I wanted to access this memory using variables but there is no convenient way to do this since every variable requires a function to access it. On Windows:gcc -o rpncalc.exe rpnmain_pc.cOn Linux:gcc -lncurses -o rpncalc rpnmain_pc.cNumbers are stored in unpacked BCD format on an external SRAM chip. You can download it from GitHub if you want to test out the functionality: rpnmain_pc.c It will compile for Windows if #WINDOWS is defined or for Linux with the ncurses library if #LINUX is defined. While I was writing the code for BCD calculations, I used a console program to test the routines. The interface shows 4 levels of the stack, similar to some HP calculators. ![]()
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