3.4.9 Wi-Fi/Bluetooth Module (Optional)

The user has the option to solder an ATWILC3000-MR110CA Wi-Fi/BT module with a chip antenna or an ATWILC3000-MR110UA Wi-Fi/BT module with a U.FL connector.

The ATWILC3000-MR110PA WLAN PHY is designed to achieve a reliable and power-efficient physical layer communication as specified by IEEE® 802.11 b/g/n in Single Stream mode with a 20-MHz bandwidth. Advanced algorithms are used to achieve maximum throughput in a real-world communication environment with impairments and interference. The PHY implements all required functions such as FFT, filtering, FEC (Viterbi decoder), frequency and timing acquisition and tracking, channel estimation and equalization, carrier sensing and clear channel assessment, as well as automatic gain control. The module is available in a fully certified, 22.428 x 17.732 mm, 36-pin module package. For more information about the ATWILC3000, refer to the product web page.

Figure 3-46. Wi-Fi/Bluetooth Interface Schematic
Table 3-38. Wi-Fi/Bluetooth Signal Descriptions
PIOSignal NameSharedSignal Description
PD5SDMMC2_WILC3000_DAT0_PD5SDIO data
PD6SDMMC2_WILC3000_DAT1_PD6SDIO data
PD7SDMMC2_WILC3000_DAT2_PD7SDIO data
PD8SDMMC2_WILC3000_DAT3_PD8SDIO data
PD3SDMMC2_WILC3000_CMD_PD3SDIO command
PD4SDMMC2_WILC3000_CK_PD4SDIO clock
PE4BT_TX_FLEXCOM0_IO1_PE4 40-pin RPi connectorBluetooth serial TX

(RX into SAMA7G5)

PE3BT_RX_FLEXCOM0_IO0_PE340-pin RPi connectorBluetooth serial RX

(TX from SAMA7G5)

PE6BT_RTS_FLEXCOM0_IO3_PE640-pin RPi connectorBluetooth serial RTS
PE7BT_CTS_FLEXCOM0_IO4_PE740-pin RPi connectorBluetooth serial CTS
PD2SDMMC2_WILC3000_RSTN_PD2Module reset
PD10WILC3000_INT_PD10Interrupt
PE0WILC3000_EN_PE0Chip enable

Special care must be taken when powering the ATWILC3000 wireless module. Due to the nature of the wireless transmission, the module draws much current from its supply rail. In the worst-case scenario, the module can draw up to 300 mA.

To address this power consumption, the module is fitted with its own separate power supply, the MCP1725, which is a 500-mA low dropout (LDO) linear regulator that provides high current and low output voltages in a very small package. For more information about the MCP1725, refer to the product web page.

The MCP1725 was chosen because it can supply the current required by the module, and because it features a shutdown input pin (SHDN) and a power good output pin (PWRGD):

  • The SHDN input allows to shut down the wireless module when unused, therefore saving power.
  • The PWRGD output ensures that the ATWILC3000 wireless module is kept in reset until its power rails are stable.
Figure 3-47. Wi-Fi/Bluetooth Enable Schematic
Note: When the ATWILC3000 module is enabled, the Flexcom SPI cannot be used with the RPi 40-pin connector.