Texas Instruments OMAP5912 Reference Manual page 451

Configuration
34 Initialization
Pullup and pulldown control has changed from OMAP5910 to OMAP5912. As
applicable, the OMAP5910 device has either a pullup or a pulldown per pin,
and a 1-bit register per pin enables or disables the pullup or pulldown. The
OMAP5912 device, however, has both a pullup and a pulldown available on
each pin. Thus, a new OMAP5912 register set is implemented (PU_PD_SEL
(0-4)) to allow the software to select between the use of a pullup or a pulldown
on each pin. The reset condition of PU_PD_SEL(0-4) is determined, to keep
compatibility with the OMAP5910 reset condition. The OMAP5910
pullup/pulldown enable register set remains (PULL_DWN_CTRL (0-3). The
reset state, however, is changed to match what the pinout requires at reset.
In the OMAP5910, programming of the following registers does not take effect
until the COMP_MODE_CTRL_0 register is written with 0x0000EAEF. For
OMAP5912, however, these registers do not have this restriction, and
programming the register takes effect immediately, regardless of the state of
the COMP_MODE_CTRL_0 register.
GATE_INH_CTRL_0
-
VOLTAGE_CTRL_0
-
TEST_DBG_CTRL_0
-
MOD_CONF_CTRL_0
-
For OMAP5912, all I/O power supplies have a low- and a high-voltage mode
VS. In OMAP5910, only the EMIFS, EMIFF, and communication processor
interface have dual voltage interfaces. For OMAP5912 at reset, the voltage
mode has changed to default to low-voltage mode, whereas in OMAP5910 it
is high-voltage mode.
The OMAP5912 software/hardware compatibility summary for I/O
multiplexing and configuration is as follows:
The device resets to functional multiplexing mode 000 with appropriate
-
pullups or pulldowns configured and enabled to preserve the OMAP5910
pinout reset condition if RESET_MODE pin is set to 0.
Multiplexing-per-pin stays the same as in the OMAP5910 mode. More
-
pins are multiplexed in OMAP5912, so that there are additional
FUNC_MUX_CTRL registers.
The PULL_DWN_CTRL register set remains unchanged. It is responsible
-
for pullup or pulldown enable, as determined by the state of the newly
created PU_PD_SEL register set. Because there are additional pins
requiring pullup/pulldown capability, extra PULL_DWN_CTRL registers
have been added. Because not all pins need a pullup or pulldown function,
see the OMAP5912 Application Processor Data Manual (SPRS231) to
determine whether a pullup/pulldown is implemented.
SPRU752B