Expansion Board Minimum Requirements:
- Method for connecting Intel® Joule™ module to expansion board:
The module must be securely mounted to an expansion board in a method that maintains full engagement of the board-to-board interface connectors. See Module Retention for more details.
- Method to provide +VSYS power to the module:
♦ The module requires a +VSYS source routed through 12 pins, 6 on each board-to-board connector, which must all be connected in common to balance the current path.
♦ Connect +VSYS to VDCIN_SENSE or USB +VBUS to VBUS_SENSE to trigger a module boot.
♦ Voltage minimum: 3.6 V, typical: 4.2 V, maximum: 5.25 V, with a current capability of 4 A
- Required strapping of module pins:
♦ The module pin strappings in Required Straps must be implemented for boot during the rising edge of PMIC_PWRGOOD (J6, pin 33). See also Boot Strap Signal Isolation for a recommended isolation circuit.
♦ Module strap pins can be left unconnected if not used.
Expansion Board Recommendations:
- Power button (recommended, preferred on all designs):
Connect an active, low-power button to J6 pin 9 to trigger a reset or to power cycle the board.
- DnX button (high importance, include if BIOS flashing support is needed. Add a test point for access if the DnX button is not included.):
Connect an active, high (+VDD1) signal to J6, pin 78, to initiate a download and execute a routine that updates the BIOS through the USB 2.0, port 0. This DnX button signal is the only way to initiate the download and execute the update process.
- USB 2.0 device connector routed to port 0 to enable DnX BIOS updates.
- UART debugging (critical, preferred on all designs):
Include a method to access UART port 2 on the module during boot, to collect debug information. This is the only way to access debug messages generated during the power on and boot sequences.
- External EEPROM to hold board identification and manufacturing data.
- USB 3.0 host connector for general purpose device use; recommend implementing USB host support.
- Real-Time Clock (RTC) backup power source (optional, implement if RTC support needed):
A backup power source is required for the RTC to operate robustly; this prevents RTC data losses during unexpected power loss. The most common solution is a non-rechargeable, coin-cell battery connected to +VRTC at module connector J6, pin 11. +VRTC voltage range is from 2.05 V to 3.3 V.
- HDMI display connector with proper level conditioning appropriate for module.
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