BrightSign LS322 Hardware - Manual (Page 13)

LS322, LS422 User Manual and Operations Guide
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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, 2015
THEORY OF OPERATION
Power Supply
There are five voltages present in the player: 5V, 3.3V, 2.5V, 1.5V, and 1.2V. The 3.3V level for the USB port is created
from 12V using a switching regulator. Similar regulators are used to create the 2.5V level for the DDR SDRAM and the
1.2V level for the CPU core voltage.
BCM7208 CPU
The LS322 and LS422 utilize a BCM7208 Multimedia CPU.
Built-in Flash
The boot code in the BCM7208 instructs it to continue the boot process by reading additional code from the onboard
NAND flash, which can be updated in the field from either SD or USB storage. 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 LS322 and LS422 each contain a single bank of 2Gb (256MB) DDR SDRAM. When the BCM7208 boots, it will copy
the code from the NAND flash device into the SDRAM and then execute the code from the SDRAM. The SDRAM runs at
a clock rate of 667MHz, with a data rate of 1333MHz.
Audio Outputs
The LS322 and LS422 each have a single high quality audio DAC device, which takes in digital audio signals from the
CPU in I2S audio format. The AUD_LRCIN is the framing signal for the audio and runs at the frequency of the audio
source (usually either 44.1KHz or 48KHz). The AUD_BITCLK signal is typically 32 times higher than the AUD_LRCIN.