CPU Schematics

Configuration

• CPU configuration is written on schematics (DDR speed, CPU frequency, Ratios, L2 cache…)
• If there are free GPIO, plan to use them as configuration or board identification inputs using pull up or pull down.

JTAG

• Check JTAG signals are correctly connected to CPU
• Check JTAG SReset signal is correctly connected to system reset
• Check if JTAG SRST and TRST needs pull up resistors
• If multiples TMS signals are available on CPU, use shunt resistor to be able to change easily

NAND

• NAND pins are connected to CPU capable nand pins
• NAND WP pin is pulled correctly
• NAND RDY signal has correct pull up
• If NAND is a boot device, check that configuration is correct

SPI

• SPI pins are connected to CPU capable nand pins
• If SPI is a boot device, check that configuration is correct

PCI Express

• Check calibration resistors value
• Check if CLKREQ is correctly connected
• Check that there is a serial capacitor on each RX/TX line signal (100nF/0402)
• Check that there is a 50 Ohm pulldown resistor on each Clock signal
• Check that clock frequency is 100MHz

Ethernet

• Check that ethernet signals are connected to hardware capable pins
• Check signal voltage level
• Check that GE_MDIO has a 2kOhm pullup resistor

RGMII

• In RGMII, check if there is a need of delay function

SGMII

• In SGMII, check that there is a 10nF serial capacitor on TX and RX signals
• Check that SGMII signals are connected to the right Serdes port

SATA

• Check SATA calibration resistor value
• Check that SATA signals are connected to hardware capable pins
• Check that there is a 10nF serial capacitor on each TX and RX SATA signal

I²C

• Check that there is a 4.7KOhms pull up resistor on Clock and DATA signals
• List all used bus address and check that here is on conflict
• Check voltage levels

Reset

• Check that there is a pull up resistor on reset signal
• Check that reset meets timing requirement