7.1 List of Unmounted Elements

Two types of unmounted components are listed in this section:

In blue, the components that can be mounted, with some board adaptation, without any damage to the system.
In red, unmounted components used for factory and debug configuration. Those should never be mounted, as such action could result in damage or destruction of the board or system elements.

Figure 7-1. Unmounted Components Overview: Top View

The following table lists the top side unmounted components and their functionalities.

Table 7-1. Top Side Unmounted Elements
Ref.	Type	Feature	Color Status	Used for	What to do if mounted
C76	Capacitor	24 MHz	Blue	Crystal load capacitance	Remove R34 and R36.
C81	Capacitor	24 MHz	Blue	Crystal load capacitance
R37	Resistor	24 MHz	Blue	Crystal selection
R40	Resistor	24 MHz	Blue	Crystal selection
Y3	Crystal	24 MHz	Blue	24 MHz crystal
R39	Resistor	24 MHz	Red	Crystal measurement	Only use in factory. If mounted, the crystal behavior will be degraded.
C165	Capacitor	25 MHz RGMII	Blue	Crystal load capacitance	Remove R171.
C166	Capacitor	25 MHz RGMII	Blue	Crystal load capacitance
R167	Resistor	25 MHz RGMII	Blue	Crystal selection
R168	Resistor	25 MHz RGMII	Blue	Crystal selection
Y5	Crystal	25 MHz RGMII	Blue	25 MHz crystal
C192	Capacitor	25 MHz RMII	Blue	Crystal load capacitance	Remove R178.
C193	Capacitor	25 MHz RMII	Blue	Crystal load capacitance
R181	Resistor	25 MHz RMII	Blue	Crystal selection
R184	Resistor	25 MHz RMII	Blue	Crystal selection
Y8	Crystal	25 MHz RMII	Blue	25 MHz crystal
R183	Resistor	25 MHz RMII	Red	Crystal measurement	Only use in factory. If mounted, the crystal behavior will be degraded.
R35	Resistor	32 kHz	Red	Crystal measurement	Only use in factory. If mounted, the crystal behavior will be degraded.
U20	Module	ATWILC3000	Blue	ATWILC3000 module	–
J15	Connector	Debug	Blue	WILC3000 debug interface	–
J16	Connector	Debug	Blue	WILC3000 debug interface	–
R232	Resistor	Debug	Blue	Debug CTS pull-up	–
R233	Resistor	Debug	Blue	Debug RTS pull-up	–
R179	Resistor	nRST_OUT	Blue	nRST selection instead of NRST_OUT	Remove R180.
R118	Resistor	SD Card	Red	SDMMC1_1V8_SEL pull-up	–
C127	Capacitor	Supply	Red	VLDO1 decoupling	– Note: Excessive capacitor load on the MCP16502 DCDC or LDO lines can result in output instability and power-on sequence failure.
C128	Capacitor	Supply	Red	VDD_3V3 decoupling
C220	Capacitor	Supply	Red	VDD_3V3_WILC decoupling
C240	Capacitor	System	Blue	nSTART decoupling and startup configuration	The product starts automatically.
J14	Connector	Tamper	Blue	Tamper pins use	–
R164	Resistor	Ethernet RGMII	Red	Gigabit Ethernet 125 MHz clock line	–

Figure 7-2. Unmounted Components Overview: Bottom View

The following table lists the bottom side unmounted components and their functionalities.

Table 7-2. Bottom Side Unmounted Elements
Ref.	Type	Feature	Color Status	Used for	What to do if mounted
C77	Capacitor	32 kHz	Blue	MEMS oscillator decoupling	Remove Y1, C66 and C72.
R38	Resistor	32 kHz	Blue	MEMS oscillator selection
Y4	MEMS oscillator	32 kHz	Blue	32 kHz MEMS generation
R266	Resistor	Debug	Red	JTAG TCK pull-up
R249	Resistor	J-Link-OB	Red	Boundary scan selection	If mounted, at boot the device enters in boundary scan. J-Link-OB will never start.
R134	Resistor	nRST_OUT	Blue	nRST selection instead of NRST_OUT	Remove R136.
R165	Resistor	nRST_OUT	Blue	nRST selection instead of NRST_OUT	Remove R166.
R198	Resistor	nRST_OUT	Blue	nRST selection instead of NRST_OUT	Remove R199.
R119	Resistor	nRST_OUT	Blue	NRST_OUT selection instead of SDMMC1_RSTN_PB28	If mounted, the SD Card can also be reset by the processor reset line.
R24	Resistor	nRST_OUT	Red	nRST_OUT pull-up	No impact
R10	Resistor	PMIC	Red	PMIC output voltage selection	Never mount this element. The VLDO1 output voltage is set to 1.8V for SD Card voltage selection. If changed, the SD Card interface might get destroyed.
C103	Capacitor	SAMA7G5	Blue	DDR_VERF decoupling	No impact
C123	Capacitor	SAMA7G5	Red	DDR_VERF decoupling
C124	Capacitor	SAMA7G5	Red	DDR_VERF decoupling
R26	Resistor	SAMA7G5	Red	Boundary scan selection	If mounted, at boot the device enters in boundary scan.
R191	Resistor	Supply	Blue	Input supply selection	Remove R185.
C167	Capacitor	Supply	Red	AVDDH decoupling	– Note: Excessive capacitor load on the MCP16502 DCDC or LDO lines can result in output instability and power-on sequence failure.
C177	Capacitor	Supply	Red	DVDDH decoupling
R148	Resistor	Ethernet RGMII	Red	TXCK pull-up	–
R153	Resistor	Ethernet RGMII	Blue	RXCTL pull-up	–