Power On Reset

The W_DISABLE1# pin on the Sona TI351 drives the radio reset input. This signal must be controlled by the host platform GPIO.

Power Supply Restrictions

The Sona TI351 SDIO interface operates at 1.8V only. The host platform SDIO interface must operate at 1.8V at all times, including during bus enumeration.

In-band vs Out Of Band Interrupts

The Sona TI351 supports either in-band (SDIO controller) interrupt or Out Of Band (GPIO) interrupts. If using GPIO-based Out Of Band interrupts the interrupt should be configured as LEVEL sensitive. If the host CPU is not able to support LEVEL sensitive interrupts, in-band must be used.

If using Out Of Band interrupts, the polarity differs between M.2 1216 and M.2 2230 modules. The M.2 1216 variant uses the HOST_IRQ_WL pin and the signal is active high. The M.2 2230 variant uses the SDIO_WAKE# signal and is active low.

Wake On Wireless

The SDIO_WAKE#/HOST_IRQ_WL signal is used to implement Wake On Wireless and must be implemented if Wake On Wireless is desired. Wake On Wireless requires using the Out Of Band (GPIO) interrupt architecture.

The SDIO_WAKE#/HOST_IRQ_WL signal does not need to be implemented if Wake On Wireless is not required.

HOST_IRQ_WL State at Boot

The SDIO_WAKE#/HOST_IRQ_WL pin on the Sona TI351 M.2 1216 solder down module is internally directly connected to the HOST_IRQ_WL pin on the CC3351. This is a SenseOnPower pin that is pulled low internally and must be low when the device powers up. It must not be pulled high or driven high by the host platform. If this cannot be guaranteed, the signal must be buffered.

The Sona TI351 M.2 2230 plugin module buffers this signal before exposing it as SDIO_WAKE# so it does not have the same restriction.

UART Hardware Handshaking Requirements

The UART interface requires RTS/CTS hardware handshaking.

In addition, the UART on the host must immediately stop transmitting when RTS is asserted. If the host sends even one byte after RTS is asserted the firmware will hang unless low level power management is disabled in TI351 firmware. Some UART controllers are unable to meet this requirement.

The UART used on FTDI serial/USB converters is known to be unable to meet this requirement.

Low level power management can be disabled by writing a ‘0’ to the ‘sleep_auth’ parameter in the cc33xx debugfs interface prior to enabling Bluetooth. This step is required if using FTDI serial/USB converters or any other UART that cannot meet this requirement.