serial_mouse: Add initial files

converter/serial_mouse/README

@@ -0,0 +1,60 @@
+Serial Mouse Converter
+======================
+This makes old serial mouse into modern USB one.
+
+Tested by:
+- Microsoft green-eyed mouse
+- DELL mouse can work with DTR only.
+
+
+Pinout
+------
+
+    DE-9    DB-25   DTE DCE     Description
+    ----------------------------------------------------------------
+    2       3       RXD TXD     data from mouse
+    3       2       TXD RXD     used by mouse as power source?
+    4       20      DTR DSR     used by mouse as power source
+    5       7       GND GND
+    7       4       RTS CTS     used by mouse as power source
+    *DTE=Converter, DCE=Mouse
+
+
+
+## RS-232 Driver
+Microsoft mouse seems to need higher voltage for power source.
+SP3232E outputs only +-6V at charge pump output and didn't work.
+ADM232A works for both Microsoft and DELL.
+
+Microsoft green-eyed mouse requires both while DELL mouse can work with DTR only.
+
+
+## Wiring
+Mouse RXD, TXD, DTR and RTS should be wired to RS-232 driver.
+Wire up RS-232 driver charge pump output V+ to DTR and RTS for power source purpose.
+
+Connect Mouse TXD to AVR PD2(RXD) *through* RS-232 driver for mouse data.
+
+
+
+UART Setting
+------------
+defined in config.h.
+
+### Microsoft serial mouse
+1200 baud, 7-bit data, no parity, 1-bit stop, lsb-first
+
+### MouseSystems
+1200 baud, 8-bit data, no parity, 1-bit stop, lsb-first(Not tested)
+
+
+Resources
+---------
+Get power out of PC RS-232 port:
+https://www.epanorama.net/circuits/rspower.html
+
+Microsoft serial mouse:
+https://web.archive.org/web/20130307230349/www.kryslix.com/nsfaq/Q.12.html
+
+Serial Mice Protocols:
+https://roborooter.com/post/serial-mice/