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CTA Calibration Flasher: Controller Board V3: Hardware Overview

A controller board to drive the CTA Calibration Flasher LED Board V3.

Top

Bottom

Dimensions

The full schematic is available here.

ATSAMD21G18A

The heart of the board is the ATSAMD21G18A processor as found on the Arduino Zero

SAMD

WIZnet W5500 and Ethernet socket

100Mb Ethernet connectivity is provided by the WIZnet W5500 Ethernet controller as found on the Arduino Leonardo Ethernet

W5500

The Ethernet socket is the Valcon VSIMJLV-88-FF-GY with integrated magnetics and LEDs and is available from Toby Electronics. The LEDs are disabled by default, link SJ1 needs to be soldered closed to enable the LEDs.

The connector shield is connected to GND through R23 (0R) and can be isolated if required.

Ethernet

IO Pins

The IO pins are spaced by 0.1" to allow standard pin headers to be soldered into place if required. The pins are:

  • SWCLK: the single wire clock used to program the Arduino Zero bootloader onto the SAMD using a Segger JLink or similar
  • SWDIO: the single wire data line used to program the Arduino Zero bootloader onto the SAMD
  • 5V: 5V power input to the board
  • GND: 0V
  • 3.3V: 3.3V output from the on-board SPX3819-3.3 regulator
  • S0_0: SCOM0 pad 0: can be used as SPI CS or I2C SDA
  • S0_1: SCOM0 pad 1: can be used as SPI SCK or I2C SCL
  • S0_2: SCOM0 pad 2: can be used as SPI CIPO or UART TX
  • S0_3: SCOM0 pad 3: can be used as SPI COPI or UART RX

Resistors R27 and R28 can be added to provide I2C pull-ups. The SW and SCOM0 signals are 3.3V.

IO_Pins

5V power is regulated down to 3.3V by an SPX3819-3.3 regulator

Vreg

SMA Connector

The external trigger pulse is connected via an SMA connector. The input is 3.3V and 5V compatible. R1 can be installed to provide a 50R input impedance if required. A 74HC1G125 acts as a buffer for the trigger signal. R29 provides current limiting for 5V inputs (the 74HC1G125 has internal clamping diodes to 3.3V and GND).

The SAMD can also generate test pulses on physical pin 48. The TEST PULSE 0.1" jumper needs to be closed to couple the test pulses from the SAMD to the 74HC1G125 input. The SMA connector then becomes an output, allowing the test pulse to be monitored.

Trigger_Buffer

USB Connector

The board is equipped with a USB 2.0 Type B socket which can be used to provide 5V power and provide a USB serial interface to the SAMD.

The board can be configured and controlled through the USB connector if required during lab testing.

The connector shield is connected to GND through R25 (0R) and can be isolated if required. Transzorbs provide protection for the data lines. D1 prevents 5V power from being back-fed to a PC if 5V power is also provided on the IO pins.

USB

LED Board Connector

The LED board connector is a Samtec FLE-108-01

Connector

The pin allocation is:

  • 1: +5V power
  • 2: GND (0V)
  • 3: I2C SDA (DS28CM00)
  • 4: SPI SCK (ADT7310)
  • 5: I2C SCL (DS28CM00)
  • 6: SPI CIPO (ADT7310)
  • 7: Photorelay A2
  • 8: SPI COPI (ADT7310)
  • 9: Photorelay A1
  • 10: SPI CS (ADT7310)
  • 11: Photorelay A0
  • 12: DS1023 Data
  • 13: Photorelay A3
  • 14: DS1023 CLK
  • 15: Trigger signal
  • 16: DS1023 Latch Enable

Reset Supervisor

The board is equipped with a MCP111T-2.4V reset supervisor to ensure the SAMD is reset correctly when power is applied to the board. (The SAMD has built-in brown-out and reset protection, but this has been found to be unreliable if the voltage rises slowly.)

Supervisor