40MX and 42MX FPGA Families
1- 12
R e v i sio n 1 1
Test Circuitry and Silicon Explorer II Probe
MX devices contain probing circuitry that provides built-in access to every node in a design, via the use of
Silicon Explorer II. Silicon Explorer II is an integrated hardware and software solution that, in conjunction
with the Designer software, allow users to examine any of the internal nets of the device while it is
operating in a prototyping or a production system. The user can probe into an MX device without
changing the placement and routing of the design and without using any additional resources. Silicon
Explorer II's noninvasive method does not alter timing or loading effects, thus shortening the debug cycle
and providing a true representation of the device under actual functional situations.
Silicon Explorer II samples data at 100 MHz (asynchronous) or 66 MHz (synchronous). Silicon Explorer II
attaches to a PC's standard COM port, turning the PC into a fully functional 18-channel logic analyzer.
Silicon Explorer II allows designers to complete the design verification process at their desks and
reduces verification time from several hours per cycle to a few seconds.
Silicon Explorer II is used to control the MODE, DCLK, SDI and SDO pins in MX devices to select the
desired nets for debugging. The user simply assigns the selected internal nets in the Silicon Explorer II
software to the PRA/PRB output pins for observation. Probing functionality is activated when the MODE
pin is held HIGH.
Figure 1-11 illustrates the interconnection between Silicon Explorer II and 40MX devices, while
Figure 1- 12 on page 1-12 illustrates the interconnection between Silicon Explorer II and 42MX devices
To allow for probing capabilities, the security fuses must not be programmed. (Refer to
"User Security"summarizes the possible device configurations for probing.
PRA and PRB pins are dual-purpose pins. When the "Reserve Probe Pin" is checked in the
Designer software, PRA and PRB pins are reserved as dedicated outputs for probing. If PRA and PRB
pins are required as user I/Os to achieve successful layout and "Reserve Probe Pin" is checked, the
layout tool will override the option and place user I/Os on PRA and PRB pins.
Figure 1-11 Silicon Explorer II Setup with 40MX
Figure 1-12 Silicon Explorer II Setup with 42MX
40MX
Silicon
Explorer II
PRA
PRB
SDO
DCLK
SDI
MODE
Serial Connection
to Windows PC
16 Logic Analyzer Channels
42MX
Silicon
Explorer II
PRA
PRB
SDO
DCLK
SDI
MODE
Serial Connection
to Windows PC
16 Logic Analyzer Channels