Instrument Circuitry – Reference 3000 Schematic/Block Diagrams
23
Figure 3-5
Microprocessors in the Reference 3000
Notes for Figure 3-5:
Note the lack of a ground connection between the USB bus and the Reference 3000 circuitry.
The EasyUSB firmware is loaded into EasyUSB RAM on power-up. The USB firmware can be updated
over the USB via a selection in the Reference 3000 section in the Instrument Manager.
The Power PC firmware is also transferred from ROM into RAM on power-up. The Power PC firmware
can also be updated over the USB via a selection in the Reference 3000 section of the Instrument
Manager. Time-critical sections of the Power PC code are kept in the processor’s fast cache memory.
The term UART refers to a Universal Asynchronous Receiver Transmitter. It converts parallel data to a
self-clocking serial bit stream. The UARTs send data at 6 Mbits/second.
The Bus Transceiver isolates bus activity on the Controller and Potentiostat boards. Only reads and
write-to locations on these boards generate bus activity. This reduces noise pick-up.
Each board in a Reference 3000 has local non-volatile data storage. This is used to save calibration
data and board-revision information. Unlike previous Gamry Instruments potentiostats, the Reference
3000 calibration data is stored in the instrument, not in a data file. When a Reference 3000 is moved
from one computer to another, its calibration remains valid.
