Jumper Settings
2-10
Blackfin Landscape LCD EZ-Extender Manual
Oscillator Disable Jumper (JP12)
The oscillator disable jumper (
JP12
) disables the 5 MHz oscillator driving
the
PPI0CLK
net and LCD display. The disabled oscillator mode is particu-
larly suited for low-power applications.
By default,
JP12
requires no jumpers. As a result, the oscillator is driving
the 5 MHz clock. You can permanently disable the oscillator by populat-
ing a jumper between
JP12.2
and
JP12.3
. The oscillator also can be
enabled or disabled via the GPIO pin of the AD7147 capacitive touch
controller. To enable or disable the oscillator, write to the respective con-
trol registers of the AD7147 controller (
U3
) and place a jumper between
JP12.1
and
JP12.2
(see
LCD Backlight Enable Jumper (JP13)
The LCD backlight enable jumper controls the power circuitry for the
LCD backlight. The disabled LCD backlight option is particularly suited
for low-power applications.
By default,
JP13
requires a jumper between
JP13.1
and
JP13.2
. When the
EZ-Extender is powered up, the backlight power circuit (
VR1
) is
OFF
.
To enable the LCD backlight, use the GPIO (
Aux
) pin of the AD7879
touch controller (
U1
). Write to the appropriate control registers of the
controller using the SPI interface of the Blackfin processor. You also can
control the LCD backlight via the
GPIO3
flag pin, which is linked to the
Blackfin processor directly. In the latter case, you do not need to
Table 2-11. JP12 Settings
Oscillator
JP12 Setting
Enabled
No jumper installed (default)
Controlled via AD7147 GPIO
JP12.1
and
JP12.2
Disabled
JP12.2
and
JP12.3
