Theory Of Operation; Power Supply; Reset; Bcm7444/7252 Cpu - BrightSign 4K Series Hardware Manual

BrightSign 4K242, 4K1042, 4K1142

THEORY OF OPERATION

This section describes how different components operate on BrightSign 4K players.

Power Supply

There are several voltage levels present in BrightSign 4K players.

Reset

BrightSign 4K players have a Low Voltage Reset circuit. This circuit will hold the RESET_L signal low until a valid 3.3V
power source is present.

BCM7444/7252 CPU

The 4K242 and 4K1042 utilize a BCM7252 CPU, while the 4K1142 utilizes a BCM7444 CPU. The CPU is reset by the
RESET_L signal from the low voltage reset circuit going into the RESET_IN pin on the CPU. When the RESET_IN pin
goes from low to high, the CPU will boot from the NAND flash.

Built-in Flash

The boot code in the BCM7252/BCM7444 instructs it to continue the boot process by reading additional code from the
onboard NAND flash, which can be updated in the field, either from a SDHC/SDXC flash card or a USB mass-storage
device. Part of the NAND flash is also used to hold non-volatile parameters. The contents of the boot flash are copied into
the SDRAM. The CPU then jumps to the boot code.

SDRAM

The 4K1142 contains six banks of DDR SDRAM (two 4GB banks and four 2GB banks), while the 4K242 and 4K1042
each contain four banks of DDR SDRAM (two 2GB banks and two 4GB banks). When the CPU boots, it will copy the code
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All information provided in this reference manual applies to products under development. The characteristics and specifications of these products are subject to
change without notice. BrightSign assumes no obligation regarding future manufacturing unless otherwise agreed to in writing. © BrightSign LLC, 2014