Currently blocked by this issue.
// CFG_PIN_GLUE_DAT = 5
// CFG_PIN_GLUE_CLK = 6
NRF_GPIO->PIN_CNF[CFG_PIN_GLUE_DAT] = pinDisconnectInputBuffer | (GPIO_PIN_CNF_DIR_Output << GPIO_PIN_CNF_DIR_Pos);
NRF_GPIO->PIN_CNF[CFG_PIN_GLUE_CLK] = (GPIO_PIN_CNF_DIR_Output << GPIO_PIN_CNF_DIR_Pos);
NRF_SPI0->PSEL.SCK = CFG_PIN_GLUE_CLK;
NRF_SPI0->PSEL.MOSI = CFG_PIN_GLUE_DAT;
NRF_SPI0->PSEL.MISO = SPI_PSEL_MOSI_CONNECT_Disconnected << SPI_PSEL_MOSI_CONNECT_Pos; // unused
// WARN - pins appear not be set, see screenshot! Huh?!?
NRF_SPIM0->ENABLE = SPIM_ENABLE_ENABLE_Enabled << SPIM_ENABLE_ENABLE_Pos;
NRF_SPI0->TXD = 15;
while (!NRF_SPI0->EVENTS_READY) {} // STUCK HERE. Does writing to TXD auto trigger a send?
NRF_SPI0->EVENTS_READY = 0;