- cmd_array[1] = OLED_BLOCK_SIZE * update_start % OLED_DISPLAY_WIDTH;
- cmd_array[4] = OLED_BLOCK_SIZE * update_start / OLED_DISPLAY_WIDTH;
+ // Calculate commands to set memory addressing bounds.
+ uint8_t start_page = OLED_BLOCK_SIZE * update_start / OLED_DISPLAY_WIDTH;
+ uint8_t start_column = OLED_BLOCK_SIZE * update_start % OLED_DISPLAY_WIDTH;
+#if (OLED_IC == OLED_IC_SH1106)
+ // Commands for Page Addressing Mode. Sets starting page and column; has no end bound.
+ // Column value must be split into high and low nybble and sent as two commands.
+ cmd_array[0] = PAM_PAGE_ADDR | start_page;
+ cmd_array[1] = PAM_SETCOLUMN_LSB | ((OLED_COLUMN_OFFSET + start_column) & 0x0f);
+ cmd_array[2] = PAM_SETCOLUMN_MSB | ((OLED_COLUMN_OFFSET + start_column) >> 4 & 0x0f);
+ cmd_array[3] = NOP;
+ cmd_array[4] = NOP;
+ cmd_array[5] = NOP;
+#else
+ // Commands for use in Horizontal Addressing mode.
+ cmd_array[1] = start_column;
+ cmd_array[4] = start_page;