7
The Finger Board II was designed to allow our LCD module to mount directly on top using a header
and socket with the communications board attached.
Optional parts installation
Step 22 SRAM Battery Backup
If you plan to use a standard 256kbit SRAM memory chip and not the Dallas battery backed memory
module, install diodes D4 and D5. Place the cathode side of the diodes to line up with the
silkscreened bar on the PCB.
Do not bridge solder pad J5.
D4, D5 – IN5817
Note:
Placing a 3 to 5 volt battery on header JP19 will retain the SRAM memory when the main supply
voltage is disconnected. We do recommend using the Dallas battery backed memory chip, as it is
very reliable. However if you do use standard SRAM memory, use a good quality on/off switch for the
power. Power cycle switch bounce can corrupt the data in memory.
Step 23 Remote Serial Reset
To use the remote serial port reset feature, install mosfet Q1 and bridge solder pad J3.
Q1 - BS170 or MOSFET N
Note:
If you plan to use Interactive C, do not implement this feature
