Last time I introduced my EPD project’soverview.Today, I introduce the ED050SC3 Electric Paper Display.
This screen size is 5 inch and resolution is 800 x 600 dots. The datasheet is here.
This is too old EPD. It manufactured since 2008. But we can still get it as maintenance parts.
The ED050SC3 has 33pin 0.5mm pitch Flat Flex Cable (FFC/FPC). It was very important to choose EPD.The recent EPDs needs a special connector. it is difficult to get or expensive.but we can find the FFC connector easily. For example thelist of searched at Digikey.
There are 8pins for power source, 10pins for control signals and 8pins for data transfer. 7pins are not connection.
pink is power.yellow is control signals.blue is data.
The power source
The ED050SC3 need many kind voltage power sources.
VNEG(-15V) and VPOS(+15V) are for source driver. VGG(+22V) and VEE(-20V) are for gate driver. VDD(+3.3V) and VSS(GND) is for digital logic. There need power on sequence. VDD -> VNEG,VEE -> VPOS,VGG. The delay needs longer 100us.
VCOM(-2V) is for common connection. It affected to displayed image. When the EPD is active ( turn on the device), The supplied voltage is -2V(from -1V to -2.5V). I didn’t find the affect to displayed image difference from -1V to -2.5V. This power source’s impedance should be low. If it is high ( about >100ohm ), displayed image is low contrast. And if the EPD is turn off ( cut the power source ), VCOM pin should be high impedance. Otherwise the screen’s color is changed to gray little by little after the power cut off.
BORDER(-15V, +15V or no connection) is set the border color around the screen. The border color is white, if it ties to -15V. Black is +15V. It is no connection if you never mind to color.
The control signals
There are two drivers into EPD. They are the source driver and the gate driver. The source driver controls 800 dots data for horizontal direction. The gate driver controls 600 lines data for vertical direction. These control signals sequence were not written on the datasheet. So I have hacked the e-book reader by logic analyzer. The detail is here( sorry written in Japanese. I may tartrate it to English later. )
The source driver
You need control XCL, XLE, XOE and XSTL2.
XCL take the data signals(8bit) in source driver when the rising edge.
XLE set high when the one line data (800 dots) are finished to transfer.
XOE set high basically for data transfer period.
XSHR is tied high. It was not working when it was tied to low.
XSTL2 set low before start to transfer the data.
The gate driver
You need control the MODE(1,2), SPV, CKV pin.
MODE1 and MODE2 are tied together. MODE is set high first of all control signals.
XRL is tied high. It was not working when it was tied to low.
SPV is set low before start to transfer the first line data.
CKV is set high to change next line.
These control signals are complicated in
actuality wave forms. Please see this also.
The data signals
It is 8bit data width. It can transfer 4 dots data once. the one pixel is consisted of two bits. 1 0 is changing to white. 0 1 is black. 0 0 is no changing. 1 1 is also no changing but may be damaged to EPD.
ED050SC3(LF) and ED050SC3(LF) H1
There are two type models the Non H1 and H1.
It doesn’t write on the datasheet difference about it. The function
was the same when it connect
to e-book. But if it was connected to microcontroller and the data
transfer speed is
slow, the displayed image was different.Please see a follow picture.
Contents of the EPD project