Dev Board Datasheet Version 1.6 Version 1.6 (July 2020) Copyright 2020 Google LLC. All rights reserved.
Features Edge TPU System-on-Module (SoM) NXP i.MX 8M SoC (Quad-core Arm Cortex-A53, plus Cortex-M4F) Google Edge TPU ML accelerator coprocessor Cryptographic coprocessor Wi-Fi 2x2 MIMO (802.11b/g/n/ac 2.4/5 GHz) Bluetooth 4.2 8 GB eMMC 1 or 4 GB LPDDR4 USB connections USB Type-C power port (5 V DC) USB 3.0 Type-C OTG port Audio connections 3.5 mm audio jack (CTIA compliant) Digital PDM microphone (x2) 2.54 mm 4-pin terminal for stereo speakers Video connections HDMI 2.
Ordering information Part number Description G950-01455-01 G950-03970-01 G950-04742-01 Coral Dev Board with 1 GB RAM (part number varies by region) G950-06210-01 Coral Dev Board with 4 GB RAM Version 1.6 (July 2020) Copyright 2020 Google LLC. All rights reserved.
Table of contents System components Block diagrams Mechanical dimensions Baseboard connections I/O header pinout Serial console port HDMI port USB 3.
System components Table 1. Available Dev Board components and features Feature Details Main system-on-chip (i.MX8M) Arm Cortex-A53 MPCore platform Quad symmetric Cortex-A53 processors: 32 KB L1 Instruction Cache 32 KB L1 Data Cache Support L1 cache RAMs protection with parity/ECC Support of 64-bit Armv8-A architecture: 1 MB unified L2 cache Support L2 cache RAMs protection with ECC Frequency of 1.
Feature I/O connectivity Details 2x USB 3.0/2.
Feature Details Display HDMI Display Interface: HDMI 2.
Feature Edge TPU coprocessor Details ASIC designed by Google that provides high performance ML inferencing for TensorFlow Lite models Uses PCIe and I2C/GPIO to interface with the iMX 8M SoC 4 trillion operations per second (TOPS) 2 TOPS per watt Memory and storage Random access memory (SDRAM) 1 or 4 GB LPDDR4 SDRAM (4-channel, 32-bit bus width) 1600 MHz maximum DDR clock Interfaces directly to the iMX 8M build-in DDR controller Flash memory (eMMC) 8 GB NAND eMMC flash memory 8-bits MMC mode Conforms to
Feature Details Baseboard Connectors 40-pin I/O header (see pinout below) USB Micro-B for serial console USB 3.0 Type-A host Gigabit Ethernet 4-pin stereo terminal 3.5 mm audio jack USB Type-C power USB Type-C data HDMI 2.0a (full size) MicroSD slot MIPI DSI display (39-pin flat flex cable) MIPI CSI-2 camera (24-pin flat flex cable) Version 1.6 (July 2020) Copyright 2020 Google LLC. All rights reserved.
Block diagrams Figures 1 and 2 illustrate the core components on the baseboard and SoM. Figure 1. Block diagram of the baseboard components Version 1.6 (July 2020) Copyright 2020 Google LLC. All rights reserved.
Figure 2. Block diagram of the SoM components Version 1.6 (July 2020) Copyright 2020 Google LLC. All rights reserved.
Mechanical dimensions Figure 3. Coral Dev Board dimensions Version 1.6 (July 2020) Copyright 2020 Google LLC. All rights reserved.
Baseboard connections The baseboard on the Coral Dev Board provides a variety of connectors as shown in figure 4. Figure 4. Connectors on the Coral Dev Board I/O header pinout All I/O pins on the 40-pin header are powered by the 3.3 V power rail, with a programmable impedance of 40255 ohms, and a max current of ~82 mA. All I/O pins have a 90k pull-down resistor inside the iMX 8M SoC that is used by default during bootup, except for the I2C pins, which instead have a pull-up to 3.3 V on the SoM.
Table 2. Pinout for the 40-pin I/O header. (For detailed usage information, see Connect to the Dev Board I/O pins.) SoC signal name Baseboard signal Header pins Baseboard signal SoC signal name +3.
Universal Asynchronous Receiver-Transmitter (UART) Each UARTv2 module supports the following: 7- or 8-bit data words, 1 or 2 stop bits, programmable parity (even, odd, or none). Programmable baud rates up to 4 Mbps. 32-byte FIFO on Tx and 32 half-word FIFO on Rx supporting auto-baud. Note: By default, the Mendel operating system configures UART1 for use with the the serial console.
Connect with Linux . Run the following commands to add the required udev rule: sudo sh -c "echo 'SUBSYSTEM==\"usb\", ATTR{idVendor}==\"0525\", MODE=\"0664\", \ GROUP=\"plugdev\", TAG+=\"uaccess\"' >> /etc/udev/rules.d/65-edgetpu-board.rules" sudo udevadm control --reload-rules && udevadm trigger . Determine the device filename for the serial connection by running this command on your Linux computer: dmesg | grep ttyUSB You should see two results such as this: [ 6437.706335] usb 2-13.
Help! If screen prints Cannot access line '/dev/ttyUSB0', then your Linux user account is not in the plugdev and/or dialout system group. Ask your system admin to add your account to both groups, and then restart your computer for it to take effect. If you see [screen is terminating], it might also be due to the system groups, or there's something else wrong with screen—ensure all screen sessions are closed (type screen -ls to see open sessions), unplug the USB cable from the Dev Board, and then try again.
4-pin stereo terminal We recommend using a 4 ohm, 3 watt speaker. A higher ohmage results in a much quieter output. The stereo terminal is a 4-pin 2.54 mm-pitch terminal connector for stereo speakers. Wire functions are as follows (from left to right, as shown in figure 5): 1: Speaker left positive 2: Speaker left negative 3: Speaker right positive 4: Speaker right negative Figure 5. Stereo speaker terminals MicroSD slot The MicroSD card meets the SD/SDIO standard, up to version 3.0.
MIPI DSI display connector The MIPI DSI display connector is a 39-pin flex cable connector that provides 4 lanes with resolution up to 1920x1080 at 60 Hz. The connector pinout is as follows. Table 3.
MIPI CSI-2 camera connector pinout The MIPI CSI-2 camera connector is a 24-pin flex cable connector that's designed for the Coral Camera. The connector pinout is as follows. Table 4.
Figure 6. Camera adapter card diagram Version 1.6 (July 2020) Copyright 2020 Google LLC. All rights reserved.
System power The Coral Dev Board must be powered by 2-3 A at 5 V DC using the USB Type-C power port (see figure 4). Caution: Do not attempt to power the board by connecting it to your computer. The SoM has one primary PMIC (BD71837MWV) from Rohm for the iMX 8M SoC complex, LPDDR4, eMMC, and WiFi/Bluetooth. It integrates 8 DC-DC buck regulators and 7 LDOs to provide all power rails required by iMX 8M SoC and commonly used peripherals.
System reset You can restart the system with the RESET button shown in figure 8. Figure 8. System reset button Software and operation The Dev Board factory setting includes only the U-Boot bootloader software on the eMMC memory. To use the board, you need to flash the Mendel operating system (a derivative of Debian Linux). For instructions, see the Get started guide. The Mendel system includes software that's specially-designed for the Dev Board and required to operate the Edge TPU.
Caution: Do not unplug the Dev Board to shut it down. Doing so could corrupt the system image if any write operations are in progress. Instead, safely shutdown the system with the following command: sudo shutdown now When the red LED on the Dev Board turns off, you can unplug the power. LED behavior The Dev Board has two sets of on-board LED lights: one LED for power status, and a pair of LEDs providing the status of the serial port. The Ethernet port also has a pair of LED lights.
Figure 9. Coral SoM dimensions without the heat sink and fan Recommended operating conditions To ensure reliable operation and performance, the board should operate in the following environment: Temperature: 0-50° C Thermal solution To maintain functional heat levels the Dev Board includes a heat sink and a fan with the following specifications: Speed: 9k RPM Airflow: 138 LPM (4.9 CFM) Voltage: 5 V DC Power (peak): 0.65 W Static pressure: 42 Pa (0.
Environmental and mechanical reliability tests Table 6.
Country Agency Taiwan BSMI/NCC Australia RCM New Zealand RCM India WPC Thailand NBTC Singapore IMDA Oman TRA Philippines NTC Schematic and layout les Table 8. Dev Board schematics, layout, and 3D files File Description Coral-Dev-Board-baseboard-schematic.pdf Baseboard schematic in PDF Coral-Dev-Board-baseboard-schematicAltium.zip Baseboard schematic files in Altium format Coral-Dev-Board-baseboard-layout-Allegro.brd Baseboard CAD layout in BRD format Coral-Dev-Board.
Document revisions Table 9. History of changes to this document Version Changes 1.6 (July 2020) Added part numbers for all SKU variants. 1.5 (June 2020) Correction to MIPI-CSI2 count. 1.4 (April 2020) Updated the 40-pin I/O header pinout to be searchable. 1.3 (January 2020) Added information on LED behavior. 1.2 (August 2019) Added schematic and layout files 1.1 (August 2019) Camera cable pinout corrected. 1.
