Technical Manual

Table Of Contents

The Analog + Digital I/O Interface Board

2.1.3. The Analog + Digital I/O Interface Board

The two identical interface boards ensure the connection between the main board

and the outside world (see Figure 3). The interface boards contain two connectors

each (

I/O A

and

I/O B

I/O C

and

I/O D

respectively) and some active/passive

components protecting the inputs. Each of the

I/O

connectors can accept:

• Three analog inputs

• One digital Input or Output (its function can be switched under program con-

trol, also remotely)

• One pulse counter input

Depending on the way R3 and R4 are populated, the power supply to the I/O de-

vices can be either switched or permanent. This option is factory programmable

only. If R3 is populated, the power will be permanently applied to the sensors while

if R4 is populated, the power will be applied for a deﬁned time (typically 2 seconds)

only shortly before the microcontroller samples the inputs.

2.1.4. The Power Supply and the Serial Interface

The

POWER

connector allows for:

• External supply (battery or any DC source from

5.6 to 10 volts)

• External charge supply (either a solar panel or

an AC adapter) if an internal rechargeable bat-

tery is used

• Communication over serial lines, at 19200 baud

Note: The serial line is 3 volt CMOS compatible, therefore a special adapter cable

must be used to reach the RS-232 levels. Also, if an external battery is used,

the internal battery must be disconnected.

RxD

TxD

Ground

Battery

Ext Power