EVB-LAN9252-3PORT EtherCAT
®
ESC PHY Connection Mode User’s Guide
DS50002403A-page 16
2015 Microchip Technology Inc.
3.2.1
Strap Options
The following tables describe the default settings and jumper descriptions for the
EVB-LAN9252-3PORT. These defaults are the recommended configurations for eval-
uation of the LAN9252. These settings may be changed as needed, however, any devi-
ation from the defaults settings should be approached with care and knowledge of the
schematics and datasheet. An incorrect jumper setting may disable the board.
3.2.1.1
JUMPERS J4:J9 AND J15:J16
Jumpers J4 through J9 and J15 through J16 set various functions of the LAN9252.
They can also be used as GPIOs, LED drivers. When used as LED drivers, as they are
on the EVB-LAN9252-3PORT, they are connected a specific way to set the strap value
to a “1”, and another way to set the strap value to a “0”. Figure 4 illustrates the sche-
matics connections with the D3 circuit as a pull-up, and the D4 circuit as a pull-down.
To illuminate D3, the LAN9252 will drive the cathode of the D3 low. To illuminate D4,
the LAN9252 will drive the cathode of the D4 high.
The J4 - J15 jumpers must be configured in pairs to identical settings in order to realize
the D3 circuit or the D4 circuit. The pairings are as follows:
- J4 & J7
- J6 & J9
- J5 & J8
- J15& J16
The following subsections detail the jumper pair settings, their associated strap set-
tings, and the functional effects of setting the straps. All strap values are read during
power-up and on the rising edge of nRST signal. Once the strap value is set, the
LAN9252 will drive the LED’s high or low for illumination according the strap value. For
other designs which may use these pins as GPIOs refer to LAN9252 datasheet for
additional information. In those cases, internal default straps must be changed by an
I
2
C or SMI master or through EEPROM fields.
FIGURE 3-3:
LED STRAP CIRCUIT
