HDx22 Theory of Operation

This page describes how specific components operate on the HD222 and HD1022.

BCM7241 CPU

The HD222 and HD1022 utilize a BCM7241 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 BCM7241 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

When the CPU 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 933MHz, with a data rate of 1866MT/s.

Serial Port

The HD1022 has a built-in UART that communicates with the RS-232 level shifter. The MAX232 uses a capacitive voltage switcher to create valid RS-232 voltage levels for the transmit pin.

Audio Outputs

The HD222 and the HD1022 each have a single high quality audio DAC device, which takes in digital audio signals from the CPU in an I2S audio format. The AUD_LRCIN is the framing signal for the audio and runs at the frame rate of the audio source (usually either 44.1KHz or 48KHz). The AUD_BITCLK signal is typically 32 times higher than the AUD_LRCIN.

The audio output is fed through an amplifier and sent directly to the audio output jack. It can drive a 32Ω load with a 2V RMS signal.

On-Board LEDs

There are four on-board LEDs that indicate the following:

*The Update (Upd) and Error (Err) LEDs may flash in unison to indicate that a player cannot connect to the BSN servers during the setup or recovery process. The red and yellow flash codes may also describe an error during the firmware update process as described at right.

On-Board Switch

The on-board switch is connected to the GPIO12, which is pulled low when the service (SVC) button is pressed. Conversely, a pull-up on the button normally sets the GPIO12 to be pulled high.

Reset Switch/GPIO Button

The on-board switch is connected to the reset circuit. Pressing down the reset button will send an initial signal to the system software, and holding the reset button low for approximately 4 seconds will cause a hard reset.

SDHC/SDXC Slot

The HD222 and HD1022 series has one SDHC/SDXC slot capable of transferring a 25 Mbit/sec video stream, one 5.1 AC3 stream (pass-through), and three stereo PCM tracks simultaneously. There is no inherent limit on the storage capacity of SD cards used with the player.

NAND Flash

BrightSign players have a built-in NAND flash. All the code for the player is stored on the NAND flash. It may also be possible to store some content on the NAND flash, which is connected directly to the CPU.

Ethernet

The 10/100 Base-T Ethernet is implemented on the players by directly interfacing with the BCM7241. The player has on-board Ethernet magnetics and termination for the RJ-45 cable.

USB 2.0

The USB 2.0 high-speed host controller is implemented internally on the BCM7241 SOC. The board utilizes over-current protected switches that can be used to turn the power to USB devices on or off (or to detect over-current situations).