I think the display sharing the MIDI port via a sysex strig is VERY clever.
It also allows a very simple two pin interface on the main board.
A more serious problem is the lack of a datasheet for the 28 pin version of the Basic Atom
Pro. I called Basic Micro and they said to use the 28 pin plain Basic Atom as a reference.
Also, I think we should support the 40 pin footprint, in case the 40 pin version of the Basic
Atom Pro ever shows up.
--- In ComputerVoltageSources@yahoogroups.com, "djbrow54" <davebr@...> wrote:
>
> Just spent some time on the phone with John Loffink discussing the
> various display options. To summarize, I think there are three basic
> parameters that need to be defined.
>
> 1) Display size. How many rows and how many characters?
> Considerations include backlight power and module width. These
> modules are much larger than their display area. A 8x2 will fit in a
> 1U module. You can probably find some 16x2 that will fit into a 2U
> module. The microcontroller could be implemented to support either
> format with an additional input mode select pin.
>
> 2) Electrical interface. You want to use the 14 pin parallel
> interface LCDs to best maximize availability. You don't want to use
> this many pins as the AtomPro has limited I/O. Using the AtomPro LCD
> commands requires that you use 7 pins for the display which is still
> too many. SPI and serial are options to reduce the number of pins
> used. SPI could be shared with the DAC by using another I/O pin as
> the chip select. This obviously would not be retrofitable or code
> compatible to the PSIM. Another option is sharing hardware serial
> with MIDI (as I implemented with a MIDI sysex command). Again,
> multiple modes could be implemented with an additional input mode
> select pin (I implemented both 57600 serial and MIDI sysex in my
> microcontroller)
>
> 3) Prototcol. How do you want to communicate with the LCD? Do you
> want general purpose cursor positioning? Do you even want a cursor (I
> turned it off on the 8x2 to save a character space). Do you want
> scrolling? Do you want the second line to be contiguous with the
> first, or, is overwrite mode sufficient. Do you want horizontal
> scrolling? (I chose contiguous lines with both scrolling and
> overwrite. I also did not implement general cursor position commands
> but rather start of line1, start of line2, back 1 position, & forward
> 1 position)
>
> 4) Additional features. With a microcontroller you can use additional
> pins for extra features. I added 4 digital outputs to expand my PSIM
> capability and also a MIDI status LED. Most anything is possible.
>
> Here are some links of possible interest (sorry, they will be long).
>
> PSIM in 2U MOTM format showing number of pots, connectors, & switches:
> modularsynthesis.com/modules/synthmodules/synthmodules.htm
>
> 8x2 display in 1U MOTM format:
> modularsynthesis.com/modules/synthmodules/PSIM-Display/PSIM-Display.
> htm
>
> Partway down this page is a link to my display controller spec:
> modularsynthesis.com/modules/synthmodules/PSIM-Display/DJB-
> PSIM%20LCD%20display%20spec.pdf
>
> 20x2 display in external package (e.g. too large to panel mount):
> modularsynthesis.com/display/display.htm
>
> Comments?
>
> Dave
>