Source code and electronic designs are licensed under: 
The GNU General Public License Version 3

This is a Valentine V1 ESP interface based on the ATtiny4313 running at 20Mhz

NEW! Arduino Mega support, Sketch compatible.  See Arduino Mega section at the bottom

(Note: The ATtiny2313 should also work as I'm not using more than half the RAM or Flash)

(Note: I don't have a legacy V1 nor one that does NOT support
checksums, so this is only tested for the latest version of the V1
since I can only test what I have or have access to)

The hard part about implementing ESP packet sends is that the UART
needs to be switched in and out, and the bytes have to be paced
according to specific timing, and there is a holdoff (don't send) bit.

This device is designed to do that hard, subtle, fiddly timing stuff.
Just send it a correct frame (from SOF to EOF with valid 3rd party
device ID and checksum) and it does the rest.  It will not accept
another command until the one is echoed (if it never is, and there is
a time slice, it was invalid).

Currently, only the checksum version of ESP is supported.  Upgrade your V1.

Baud is 57600 as per spec.

See Downloads for schematic or board info when available.

The pins on the ATtiny4313 are (PDIP/SOIC)

1 Reset (nc/ISP/dW)
2 RXD PD0 - from Bluetooth Module or serial transmit
3 TXD PD1 - THROUGH A 2.2K RESISTOR to pin 11 ICP1 and V1 Data Line  (and to bluetooth/serial receive via diode)
4 XTAL1 - to 20Mhz resonator or crystal
5 XTAL2 - to 20Mhz resonator or crystal
6 INT0 PD2 nc
7 INT1 PD3 nc
8 PD4 nc
9 PD5 nc
10 GND - to ground

20 VCC - to 5v
19 PB7 nc SCK for ISP
18 PB6 nc MISO for ISP
17 PB5 nc MOSI for ISP
16 PB4 nc
15 PB3 nc
14 PB2 nc
13 PB1 nc
12 PB0 nc
11 ICP1 PD6 - to pin 3 TXD and V1 Data Line (and to bluetooth/serial receive via diode)

The ICP1 is used to create a 57600 baud software UART input and to do
timing to create proper framing and time slice.

The data stream from all devices included echoed data from the
interface will directly go out via serial (breaks may cause nulls in
the data).  Typically to bluetooth.

Data from the (bluetooth) serial interface will be stored and
validated (it has to be a valid ESP message with origin IDs 3, 4, or
5) and then sent out in the correct time slice for the originator ID.

Using a TTL serial port on /dev/ttyUSB0:

v1reShark is a stream dumper and decoder (in progress)

v1send will send simple commands, mainly to set something, e.g. option 8 turns the display off, option 9 turns it on.

I usually use "./v1reshark | uniq &", then do v1send to inquire or change things.

I'm not doing legacy mode since it would require some switching, thus
more hardware, and there isn't much advantage to just having the
display status.  For legacy, any serial port (including bluetooth
module) with just the pullup running at 19200 baud can decode the
stream by seeing if the characters returned are greater or less than
0xe0 (generally you get 0xc0 and 0xf8).  The new ATtiny1634 has two
UARTs so it would make that much easier, but for now...

(If I were to do something it would be an ESP emulator that would
convert the legacy bitstream into the infDisplay packet as close as
possible, and *maybe* emulate mute on and if possible modulate the
pullup to allow the main display to turn on and off)

Note there is a "#define ANYSLICE" that overrides the checking for 3rd
party source id 3-5.  I can simulate a concealed display by sending
0x61 packets which will turn off the main display.

ARDUINO MEGA:

bluevmega.c and Makefile.ArduMega.  Can be pasted into the IDE and
uploaded to Arduino Mega boards.  Will scan the bus and return a lot
of information, then enable alerts and print them like v1test.  See
Mega.HOWTO.txt for more info.

TODO:

Move to crystal that is an exact multiple of the baud 18.34Mhz 10ppm?
v1send - add option to ask for (factory reset?)
v1send - write user bytes, sweep stuff???
multimode? - multiple packets, one each in the 3, 4, 5 slice
Yes, I know I don't have decoupling caps - but I don't need them on the breadboard, but will add them on the planned surface mount version.