For driving the electrodes on the Chemical Microprocessor - ChµP we integrated Xlinix FPGAs of the spartan-xl family for older modules and spartan-3e family for the new modules:
--- Xilinx device attributes -----
XC3S250E XCS20XL XCS10XL
System Gates 250000 20000 10000
Logic Cells 5508 950 466
Block RAM Bits 216K - -
Distributed RAM Bits 38K 12k 6k
I/O Standards 18 5 5
Max Single Ended I/O 92 113 112
for Package CSP132 CSP144 CSP144
Package size [mm] 8x8 12x12 12x12
Pitch (pin-pin distance) [mm] 0.5 0.8 0.8
I/O Supply Voltage [V] 1.2-3.3 3.3 3.3
The modules connect to the controlling computer via a small 20-pin surface connector, which provides all supply voltages, a JTAG testinterface, the FPGA configuration and controlling interface. The logic of the FPGA is programmed by schematic entry or HDL (Verilog) which creates a Bitfile that was downloaded from the controlling host (Bio@Fox) into the FPGA.
The controller interface features are:
- set electrode to 1, 0, tristate
- set toggle frequency
- set norm/inverse duty cycle
- set active/inverse duty cycle
- read electrode state
- read version of FPGA-bitfile
- read internal status
Download setting of electrode 37 (0x25) by the serial controlling interface