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I found an old one and tried to make it work. The module can display 2 lines with 20 characters each. The datasheet will show you how to connect the LCD module. So our module uses 8 parallel lines to send data to it. In this 4-bit mode each byte is transmitted in two phases: first the 4 upper bits are transmitted, then the the 4 lower bits. We can't afford to use 11 of them just to control an LCD module. This HD has its own datasheet and counts no less than 59 pages!
The information in this datasheet applies to the LML module as well. The LML module has 14 connections that can be soldered. The connections are not numbered but you can find the numbering in the datasheet of the LML. The image is not very clear but at the left of the module there are 14 soldering contacts, formed by 2 vertical rows with 7 connections each. The numbering 1 starts with the right connection of the last row.
The used circuit is very easy. The capacitor C3 will filter out the high frequency noise. C1 and C2 are needed to work properly. The LCD module is connected to the connector J2. The Vo connection, to regulate the contrast of the module, is connected to the GND fixed contrast.
The circuit should be powered by a 5 VDC stabilized voltage. You need to add a voltage regulator and some capacitors if you don't have a stabilized voltage. My application defines an array of characters containing the String to show on the LCD.
A pointer to this array is then passed to the writeString function. This function will transmit the bytes to the LCD module. Using this program on a 16F84A microcontroller has a huge disadvantage: the limited RAM space of the 16F84, which is only 68 bytes. Each character in the lcd character array will use a single byte of RAM. I see a few possibilities to overcome this problem:. Each message can contain up to 15 characters The 16th character should always be 0. Please make sure every call to this macro contains 8 parameters.
Use NULL 0 values when you don't need any more characters. I see a few possibilities to overcome this problem: Define the lcd array as a constant. Of course this is only usable when your PIC firmware isn't too large because you lose space for your program.
You only need two hardware pins on the microcontroller. It can be used to store data, even if the power is turned off.
Many applications don't need this flash memory so you could use it to store some texts.
LM032L Version. Datasheet pdf. Equivalent
LM032L LCD Controller: Hello World!