====== Zyxel GS1920 series ======

The GS1920 series is a line of managed gigabit ethernet switches. Two revisions exist, but both are built with Realtek hardware.

^ Switch name ^ RJ45 ports ^ Combo SFP ports ^ Dedicated SFP ports ^ PoE ports ^ SoC ^
| GS1920-24 | 28 | 4 | - | - | RTL8392M |
| GS1920-24HP | 28 | 4 | - | 24 | RTL8392M |
| GS1920-48 | 48 | 4 | 2 | - | RTL8393M |
| GS1920-48HP | 48 | 4 | 2 | 48 | RTL8393M |
| GS1920-8HPv2 | 10 | 2 | - | 8 | RTL8391M |
| GS1920-24v2 | 28 | 4 | - | - | RTL8391M |
| GS1920-24HPv2 | 28 | 4 | - | 24 | RTL8391M |
| GS1920-48v2 | 48 | 4 | 2 | - | RTL8393M |
| GS1920-48HPv2 | 48 | 4 | 2 | 48 | RTL8393M |

===== Models =====
==== GS1920-24HP ====
=== Hardware ===
  * SoC: RTL839x
  * Ethernet:
    * 3× RTL8218 (to be confirmed)
    * 1× RTL???? (combo ports)
  * RAM: Nanya NT5CB64M16FP-DH, 128MiB DDR3
  * Flash: Macronix MX25L1283F, 16MiB SPI NOR
  * PoE controller: STM32F100
  * PoE PSE: 6× BCM59111
  * GPIO:
    * 1× [[RTL8231]] as GPIO expander: MII mode, device address 0x3
    * 3× RTL8231 as shift register: port status LEDs
    * HC164 shift register for device status LEDs
  * ADT7468 (I2C/SMBus) thermal controller with 3× 3-pin fan
  * Sipex SP3232 RS-232 transceiver

The serial port header J2 uses the standard [[https://en.wikipedia.org/wiki/Serial_port#Pinouts|DCE pinout]], with TX/RX on pins 2 and 3, and ground on pin 5. Port settings are 9600 baud, 8n1, with ±5.6V logic levels.

The PoE management MCU and the ADT7468 fan controller are on a shared I2C bus. The PoE MCU is at address 0x20, while the fan controller is at (fixed) address 0x2E.

=== Photos ===
^ Board ^ Pictures ^
| Overview | {{:wiki:zyxel:gs1920-24hp-front.jpg?200|device front}} {{:wiki:zyxel:gs1920-24hp-overview.jpg?200|inside overview}} |
| Main board | {{:wiki:zyxel:gs1920-24hp-main.jpg?200|main board overview}} {{:wiki:zyxel:gs1920-24hp-main-soc-memory.jpg?200|main board SoC and memory}} {{:wiki:zyxel:gs1920-24hp-main-gpio.jpg?200|main board GPIOs}} {{:wiki:zyxel:gs1920-24hp-main-fan.jpg?200|main board fan control}} {{:wiki:zyxel:gs1920-24hp-main-serial-sfp.jpg?200|main board serial port and SFP cages}} {{:wiki:zyxel:gs1920-24hp-main-back.jpg?200|main board backside}} |
| PoE daughter board | {{:wiki:zyxel:gs1920-24hp-poe.jpg?200|PoE board}}  {{:wiki:zyxel:gs1920-24hp-poe-detail.jpg?200|PoE controller ICs}} {{:wiki:zyxel:gs1920-24hp-poe-back.jpg?200|PoE board backside}}  |

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