Driving a controller-less LCD
Ale
Posts: 2,363
Well, after some serious work I got a controller-less LCD to work with the propeller. You may say: but it can drive a VGA monitor, it should be a piece of cake, well that is exactly what I thought !
I like long stories
I got for 1€ each a pair of KL6448 (640x480 monochrome LCDs) a couple of years back, but never got to the point of making them work, connector problems and so on. For a project a need a LCD so I designed a PCD with some options for connecting LCDs and positive and negative charge pumps for contrast: Forget charge pumps beyond 9 or so volts ! This displays needs 24 V, positive to GND, and 5 V for logic. I thought that with the propeller I'd be able to drive it, forget again, some level shifters are needed, so I used a pair of HCT32 (VCC at 5V) to get the 5V logic needed. A boost regulator (i.e. with inductor) is needed to get those 24 V, to avoid driving the LCD with this potential before a frame is underway, the DISPEN signal is used to drive the driver transistor inside the MC33064 (regulator).
Code for this display (just for the upper half so 640x240) is included here.
I also tryed some T6963 based displays (5V logic) without much luck, they may be initialized, but without level shifters, is wasted time, so be aware. (But a charge pump works ok for a 240x64 display, not for a 128x128).
As a side note, I have a pair of TLY-933 (Toshiba) from old Toshiba T-1000 Laptop (I believe), the pinout is as follows (It need negative contrast!), I pretend to use this display insted of the other one, because half of it will not be wasted, unless I get to use 2 propellers to drive the whole display...
1 - Frame gnd
2 - Not connected (not used de-selected through jumper SJ1)
3 - Frame signal
4 - LP (line load)
5 - SCP (serial clock)
6 - GND
7 - D1
8 - D2
9 - D3
10 - D4
11 - GND
12 - + 5V
13 - -15 V contrast
14 - contrast adjust a poti from -15V to gnd
15 - GND
It needs 4 bit of data.
This display sports 3 x T6961B that are similar in pinout to the T6A40, and 8xT7778 that have similar pinout to the T6A39.
The code only prints the message "Pacito.Sys" using 2 cogs, one for driving the LCD and one for the text, the internal Font is used.
Have fun
Ale
I'd add some photos as soon as I make them
I like long stories
I got for 1€ each a pair of KL6448 (640x480 monochrome LCDs) a couple of years back, but never got to the point of making them work, connector problems and so on. For a project a need a LCD so I designed a PCD with some options for connecting LCDs and positive and negative charge pumps for contrast: Forget charge pumps beyond 9 or so volts ! This displays needs 24 V, positive to GND, and 5 V for logic. I thought that with the propeller I'd be able to drive it, forget again, some level shifters are needed, so I used a pair of HCT32 (VCC at 5V) to get the 5V logic needed. A boost regulator (i.e. with inductor) is needed to get those 24 V, to avoid driving the LCD with this potential before a frame is underway, the DISPEN signal is used to drive the driver transistor inside the MC33064 (regulator).
Code for this display (just for the upper half so 640x240) is included here.
I also tryed some T6963 based displays (5V logic) without much luck, they may be initialized, but without level shifters, is wasted time, so be aware. (But a charge pump works ok for a 240x64 display, not for a 128x128).
As a side note, I have a pair of TLY-933 (Toshiba) from old Toshiba T-1000 Laptop (I believe), the pinout is as follows (It need negative contrast!), I pretend to use this display insted of the other one, because half of it will not be wasted, unless I get to use 2 propellers to drive the whole display...
1 - Frame gnd
2 - Not connected (not used de-selected through jumper SJ1)
3 - Frame signal
4 - LP (line load)
5 - SCP (serial clock)
6 - GND
7 - D1
8 - D2
9 - D3
10 - D4
11 - GND
12 - + 5V
13 - -15 V contrast
14 - contrast adjust a poti from -15V to gnd
15 - GND
It needs 4 bit of data.
This display sports 3 x T6961B that are similar in pinout to the T6A40, and 8xT7778 that have similar pinout to the T6A39.
The code only prints the message "Pacito.Sys" using 2 cogs, one for driving the LCD and one for the text, the internal Font is used.
Have fun
Ale
I'd add some photos as soon as I make them
