PulseBlaster
Pin Assignments
Pin#
Bit#
Pin#
Bit#
1
GND
14
GND
2
Bit 15
15
Bit 14
3
GND
16
Bit 13
4
Bit 12
17
GND
5
Bit 11
18
Bit 10
6
GND
19
Bit 9
7
Bit 8
20
GND
8
Bit 7
21
Bit 6
9
GND
22
Bit 5
10
Bit 4
23
GND
11
Bit 3
24
Bit 2
12
GND
25
Bit 1
13
Bit 0
Table 1:
Lower 16 output bits and 9 ground lines on the bracket-mounted DB25 connector.
SMA Connector Clock_Out
This SMA connector outputs the reference clock as a 3.3 V TTL signal, i.e., it generates positive-
only voltage. Note that the PulseBlaster PCI and PCIe boards use 50 MHz as the reference clock
frequency and that clock is internally multiplied to provide that actual PulseBlaster Core frequency
The output resembles a square wave if properly terminated. This signal can be measured with an
oscilloscope using either a high impedance probe at the SMA connector or a 50 ohm coaxial line that
is terminated.
SMA Connector Ext_Clk
This SMA connector can be used to input an external clock signal. Extreme care should be
exercised, and certain conditions have to be met prior to using this connector. First, before attaching
any external clock source, the internal clock oscillator must be removed from its socket. The internal
clock oscillator’s orientation should be noted - if the internal clock is reconnected, it must be inserted in
the same orientation or board damage may occur. Second, the external clock signal must be 3.3 V
TTL, i.e., a positive-only voltage - any negative voltage at the Ext_Clk connector will damage the
programmable-logic processor chip. Third, the Ext_Clk connector for certain boards is not terminated
on the printed circuit board, and a 50 ohm terminating resistor should be used externally via a T
connector placed directly at the SMA Ext_Clk connector. If the Ext_Clk is terminated, there will be a
50 ohm resistor on one the Ext_Clk pads: R401 pads for SP2 board, R200 pads for SP17 board, or
R001 for PCIe boards. Soldering a 50 ohm resistor to these pads, if not already populated, is an
alternative to using a T connector with a 50 ohm resistor.
2
Custom firmware may use a different speed reference clock and may not be internally multiplied.
2021/03/22
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