[chbot] Arc Innovations eSmart Display from last meeting

[Mark Atherton]

Well done.

-mark

At 10:20 a.m. 24/05/2013, you wrote:
>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