Oh, you mean register 0x88 and 0x89? Ouch, can be interesting, you opened a closed door! I have some spare time later so I can try something.
The datasheet (at the end) says that max SPI possible it's 20Mhz. Setting RA8875_PLLC1 = 0x05 and RA8875_PLLC2 = 0x00 will give sysClock to 30Mhz (20MHz * (5+1)) / ((1+1) * 2) = 30Mhz.
Now I can play with PLLDIVN (that should be 1..31). With 31 will give a SysClock: 20MHz * (31+1)) / ((1+1) * 2 = 160Mhz, so /3 = around 50Mhz, but max SPI speed supported by chip it's 20Mhz, need to change PLLDIVN with another division (sigh!).
So PLLDIVN = 11 -> SysClock: 20MHz * (11+1)) / ((1+1) * 2 = 60Mhz, divided by 3 give 20Mhz, this should be fine(?)
In conclusion:
RA8875_PLLC1 = 0x0C
RA8875_PLLC2 = 0x00
and set MAXSPISPEED to 20000000
I didn't try this, just fast calculations.
if you want to play with it check void RA8875::initialize(uint8_t initIndex) function:
Code:
writeReg(RA8875_PLLC1,initStrings[initIndex][0]);////PLL Control Register 1
delay(1);
writeReg(RA8875_PLLC2,initStrings[initIndex][1]);////PLL Control Register 2
delay(1);
//and maybe...
writeReg(RA8875_PCSR,initStrings[initIndex][2]);//Pixel Clock Setting Register
delay(1);
then in RA8875.h file
Code:
#if defined(__MK20DX128__) || defined(__MK20DX256__) //teensy 3, 3.1 (30Mhz max)
#define MAXSPISPEED 6600000//3300000 in READ
#elif defined(__MKL26Z64__) //teensy LC (12 or 24 Mhz max)
#define MAXSPISPEED 6600000//3300000 in READ
#elif defined(__SAM3X8E__) // due
#define MAXSPISPEED 6600000
#else //rest of the world
#define MAXSPISPEED 4000000//2000000 in READ
#endif
Btw another bell ring my ears, the pullup resistors on all SPI lines can be a sign of
SPI_MODE3 instead of
SPI_MODE0? Can't wait to try it.
Even in SPI_MODE3 there's no reason for pullup resistors and useless condensers, cannot understand why the guy at Eastrising put them, if someone have a good explaination I will really appreciate.
And...yes, the eastrising (and other) cards controls the backlight from the RA pwm so power it without configuration result in a black screen with vertical lines in background.
About test, yes, you right
, sorry for the earth attack
PS
If my fried RA8875 card will resume from dead of course...