20x2 for Picaxe OLED Driver Hardware Serial Rear write control and position read

[Graham1359]

I posted a blog on a 20x2 driver for the Winstar OLED, This is a revised version that has a Read not Write line that in most designs is wired to write and use long delays so don't miss characters. The design reads the busy flag before each write and waits for it to be zero, non busy. When reading the registers d7 is the busy bit, and the lower 7 bits are the position of the cursor of the LCD/OLED, it includes non visible locations. This code repositions the cursor to the next visible position so a stream of text will flow from line one to line 4 and wrap to the start again. The specification states 8ms is required for clear screen, but seen only a two pass through the "busy code", it is one just to check. One pass is about 600us on a 64MHz clock.

attached is the circuit diagram and the new code.
Graham