Module VK5121 is made by Vikay. Some have an EL backlight. (for example the VK5121ELYG) These modules have two on-board SED1520F controllers. You’ll need these routines to display text or graphics with a PIC16f877 or 18f452.
These routines take only 12% ROM from a 16f877 and 6% ROM from a 18f452. RAM values are even less… So there will be enough ROM & RAM left to do other things !!
All important pins are left free for later use: INT0, I²C, A/D converters and Timers.
Power save: there is a power save mode available on the module, but sadly enough this mode still takes around 3mA at 5V. This is too much for battery powered circuits! That’s why i decided to add some hardware and two routines: “lcd_power_down” and “lcd_power_up” This allows us to completely shut down the module with the software.
The Pic’s PORT D is used for data transfer. It can be shared for other uses later on.
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