Datasheet

e-Paper ESP8266 Driver Board User Manual
but 2.13-display can load data line by line only. It means before the image data writing of each
line, the command WRITE_RAM must be executed.
DATA TRANSMISSION ALGORITHM
Every time the server gets some request, it sends the word “OK” (in case of known command),
otherwise the index html page. This response initiates onload event of the xhReq object and the
client-side application sends a command again according the step index stInd (see diagram
above and file uploading.js ):
Here epdInd is the display type index n mentioned in EPDn command.
Note: for white-black displays steps 1 and 2 are missing.
The image data, which is sent as a POST request, is accumulated in the bytes buffer (see buff.h
file of the server-side application):
Here 2050 >= (about 1000 bytes of data reliablely sent to ESP8266 module + about 15 bytes
in case of 3.12-display) x 2 chars per byte.
Note: You can send more data with the same size of the buffer, but this case you must
modificate Buff__getByte function at the server-side application (file buff.h ) and byteToStr
function at the client-side application (file uploading.js ). Another way to increase the data
capacity of a request is to estimate auxiliary data of the request, but this way is complicate and
effective enogh as the first one.
Actually, there is function ReadStringUntil in Arduino, which can accumulate and return whole
string of a request, but it works very slovely. This code solution describes a while-loop, where
the POST-request is accumulated character by character and every iteration of the the loop has
the signature (last 4 characters in case of command and more characters in case of a file name
as “styles.css” or “uploading.js”) checking to define what the client needs to obtain: