Design Guidelines

Hardware Design Guidelines

The purpose of these recommendations is to secure A9500-based customers projects by providing a list of high-level guidelines. You will find here tips and tricks to minimize surprises when designing Snowball based PCB derivatives.

General rules

• Don’t make any precipitate hardware changes to the Snowball baseline which would result in a dramatic misalignment of the low-level software.
• Use the Snowball approved list of components.
• Contact your A9500 distributor to drive you with the recommendations dedicated to your project.

Hardware baseline(s)

• When starting new schematics and PCB, always start from the Snowball PDK baseline.
• When it makes sense for the project, the baseline should be extended to the Calao-systems’ tablet-kit, built upon Snowball + MOB-SKY-S9500-AVI and DAB-SKY-S9500-GPI-C01 expansion boards + ADB display adapter board.
• Have your schematics and layout reviewed by ST-Ericsson partners: A9500 Distributors or Calao-systems.

Flashing the board

• The A9500’s USB interface is the sole one supported by our flashing tools in a Snowball configuration and must be available for this purpose.

Power supplies

• The boot sequence is fixing the supply outputs from the AB8500. Swapping supply outputs could result in non bootable boards.
• The 2 decoupling capacitors for VrefDDRCA and VrefDDRDQ need to be changed from 100nF to 4.7nF.

Memories

• Use only qualified LP-DDR2 memories

Peripherals on USB OTG interface

• Preferably avoid connecting expansion devices through that interface. Use FSMC instead.

Peripherals on FSMC bus

• Preferably reuse the same devices and memory mapping as in hardware baselines or in previous projects in order to leverage on existing drivers and initialization sequence.
• Up to two device or feature can be supported on the FSMC.
• The Ethernet is already supported in Snowball.
• The ISP1763A, bringing additional two USB 2.0 host ports, is supported in the Snowball Tablet Development Kit.

Camera

• Preferably use the dedicated MIPI CSI YUV interface of A9500. A list of qualified cameras with associated driver is expected soon (example: OV5640).

Layout guidelines

• Layout guidelines can be obtained from your A9500 distributor.
• For schematics and layout review service, you can contact our hardware partner Calao-systems.