[chbot] Arc Innovations eSmart Display from last meeting

[Spencer Travers]

I have done a teardown of the device and drawn a circuit diagram.

Interfaces:
- RJ12 connector on the rear has connections to power the device (12V) and
half duplex RS485/422 data lines.
- LCD is 2x16 alphanumeric (probably HD44870 based) with 8 data lines (all
used) + 3 control lines. No backlight.
- Cancel, select, up, down push buttons.
- PWM controlled beeper.
- Smart card socket.

Internals:
- 5V power supply.
- ATMega8515 micro @4MHz
- Standard Atmel ISP header, however, it seems that ISP programming has
been disabled on the micro. Can someone else verify this?
- MAX6343LUT-T brownout IC interrupts and/or resets the MCU in a brownout
power condition on the 12V power input.
- ISL83085 RS485/422 half duplex transceiver connected between RJ12 socket
and RX/TX pins on micro.
- LTC1755EGN Smart Card interface IC connected between micro and Smart Card
socket.
- Buzzer is controlled by the OC1A pin on the micro via a FET.
- LCD backlight control via PWM is possible with the addition of a FET and
some resistors that are not populated.

Several units were marked as faulty with 'card read' errors. I suspect this
is due to bent connectors in the smart card socket.

I am going to try high voltage programming to enable the ISP port on the
micro.

This device is ideal for a remote display/controller type application. If
we can figure out programming, we could have a competition for the most
interesting application for the next meeting...

I will publish the circuit diagram over the weekend once it is finished.

Spencer
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ourshack.com/pipermail/chchrobotics/attachments/20130524/ed99c2a5/attachment.html>