Other Parts Discussed in Thread: MIDAS,
Hello everyone and thank you in advance.
I am testing a 16x2 LCD screen specifically the 'MCCOG21605B6W-FPTLWI' from 'MIDAS'. It is connected to the with the 'msp430g2553 launchpad'. The connections are described in the commented code fragment that I have attached in this message. The characters are written correctly on the LCD but the problem is the contrast, it is very very low. To see the characters I have to turn the LCD and at some angle you can see that there is written text. My question is, how does the contrast of the characters increase? The backlight adjusts it through the working cycle of the PWN which connects it to the anode (this works correctly). The initialization of the LCD is the one proposed by the manufacturer for 3V power supply:
/*
MSP4302553| |LCDDriver
|Pin 1 Boost Capacitor 1
|Pin 2 Capacitor 2 N
|Pin 3 Capacitor 2 P
Vcc (3.5V) |---------|Pin 4 Vdd (Boost Capacitor 1)
Gnd |---------|Pin 5 Gnd
P1.7|---------|Pin 6 (SDA)
P1.6|---------|Pin 7 (SCL)
P2.5|---------|Pin 8 (RST)
P2.4|---------| A (Backlight Anode)
Gnd |---------| K (Backlight Cathode)
*/
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.
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char TxData[] = // Table of LCD display initialisation commands
{ 0x00,
0x38,
0x00,
0x39,
0x14,
0x74,
0x54,
0x6F,
0x0C, //Display On, Cursor On, Cursor Blink On
0x01
};
.
.
.
And these are the values proposed by the manufacturer to initialize the 3V LCD:
INITIALIZE: (3V) MOV I2C_CONTROL,#00H ;WRITE COMMAND MOV I2C_DATA,#38H ;Function Set LCALL WRITE_CODE MOV I2C_CONTROL,#00H ;WRITE COMMAND MOV I2C_DATA,#39H ;Function Set LCALL WRITE_CODE MOV I2C_DATA,#14H ;Internal OSC frequency LCALL WRITE_CODE MOV I2C_DATA,#74H ;Contrast set LCALL WRITE_CODE MOV I2C_DATA,#54H ;Power/ICON control/Contrast set LCALL WRITE_CODE MOV I2C_DATA,#6FH ;Follower control LCALL WRITE_CODE MOV I2C_DATA,#0CH ;Display ON/OFF LCALL WRITE_CODE MOV I2C_DATA,#01H ;Clear Display LCALL WRITE_CODE
Here is the datasheet:
Do you have any idea why the characters contrast is so low?
Thanks and regards!
