Have you tried the samples in the library?
https://build.particle.io/libs/WaveshareEPaper29b/0.0.1/tab/example/EPaper29b.ino
The wiring is straight forward
// HW SPI
// CLK A3;
// DIN A5
// rest custom
const int pRESET = A0;
const int pDC = A1;
const int pCS = A2;
const int pBUSY = D7;
Epd epd(SPI, pCS, pDC, pRESET, pBUSY);
Update:
@krister.johansson, has this helped? Would be nice to respond when you get help from the community.
Update2;
How I like that, people asking for help but not bothering to respond when the got the solution presented 