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UM1855
Hardware layout and configuration
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selected with FMC_NE1 chip select. FMC_NBL0 and FMC_NBL1 signals allow selecting 8-
bit and 16-bit data word operating modes.
By removal of R18, a zero-ohm resistor, the SRAM is deselected and the STM32L476ZGT6
ports PD7, PE0 and PE1 corresponding to FMC_NE1, FMC_NBL0 and FMC_NBL1 signals,
respectively, can be used for other application purposes.
2.21.1 Limitations
The SRAM addressable space is limited if some or all of A19, A20, A21, A22 and A23 FMC
address lines are shunted to the CN12 connector for debug trace purposes. In such a case,
the disconnected addressing inputs of the SRAM device are pulled down by resistors.
Section 2.2
provides information on the associated configuration elements.
2.21.2 Operating
voltage
The SRAM device operating voltage is in the range from 2.4 V to 3.6 V.
2.22
NOR Flash memory device
M29W128GL70ZA6E, a 128-Mbit NOR
Flash memory
,
8 M x16 bit,
is fitted on the
STM32L476G-EVAL main board, in U5 position. The STM32L476G-EVAL main board as
well as the addressing capabilities of FMC allow hosting M29W256GL70ZA6E, a 256-Mbit
NOR Flash memory device. This is the reason why the schematic diagram in
Figure 41
mentions both devices.
The NOR Flash memory device is attached to the 16-bit data bus and accessed with FMC.
The base address is 0x6400 0000, corresponding to NOR/SRAM2 bank1. The NOR Flash
memory device is selected with FMC_NE2 chip select signal. 16-bit data word operation
mode is selected by a pull-up resistor connected to BYTE terminal of NOR Flash memory.
The jumper JP13 is dedicated for write protect configuration.
By default, the FMC_NWAIT signal is not routed to RB port of the NOR Flash memory
device, and, to know its ready status, its status register is polled by the demo software fitted
in STM32L476G-EVAL. This can be modified with configuration elements, as shown in
Table 25
.
Table 24. SRAM chip select configuration
Resistor
Fitting
Configuration
R18
In
Default setting.
SRAM chip select is controlled with FMC_NE1
Out
SRAM is deselected. FMC_NE1 is freed for other application purposes.
