// Pinout on Olimex:
   //
   //   GP12 CK-  GP13 CK+
   //   GP14 DO-  GP15 D0+
   //   GP16 D2-  GP17 D2+
   //   GP18 D1-  GP19 D1+

   // Assign clock pair to two neighbouring pins:
   hstx_ctrl_hw->bit[0] = HSTX_CTRL_BIT0_CLK_BITS | HSTX_CTRL_BIT0_INV_BITS;
   hstx_ctrl_hw->bit[1] = HSTX_CTRL_BIT0_CLK_BITS;
   for (uint lane = 0; lane < 3; ++lane) {
       // For each TMDS lane, assign it to the correct GPIO pair based on the
       // desired pinout:
       static const int lane_to_output_bit[3] = {2, 6, 4};
       int bit = lane_to_output_bit[lane];
       // Output even bits during first half of each HSTX cycle, and odd bits
       // during second half. The shifter advances by two bits each cycle.
       uint32_t lane_data_sel_bits =
           (lane * 10    ) << HSTX_CTRL_BIT0_SEL_P_LSB |
           (lane * 10 + 1) << HSTX_CTRL_BIT0_SEL_N_LSB;
       // The two halves of each pair get identical data, but one pin is inverted.
       hstx_ctrl_hw->bit[bit    ] = lane_data_sel_bits | HSTX_CTRL_BIT0_INV_BITS;
       hstx_ctrl_hw->bit[bit + 1] = lane_data_sel_bits;
   }