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

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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

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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 –