Connection Interfaces

Popoto Modems can connect to an external device through serial, Ethernet, USB adapter, or product-specific board-level interfaces. The interfaces available on a given unit depend on the product family and ordered configuration.

Ethernet
Availability	Available on most enclosed modems, Deckbox systems, with the exception of S-Series modems configured for serial, and OEM modem configurations with Ethernet exposed through the product interface.
Pros	Ethernet provides the highest-speed and most flexible host connection for Popoto command sockets, host APIs, real-time PCM capture, and software updates.
Cons	Ethernet typically adds approximately 200-300 mW of power consumption. Standard copper Ethernet cable length is also limited to approximately 100 meters.

Refer to Interface Control for the exact connector, pinout, voltage level, and cable details for the selected Popoto Modem.

RS-422 4-Wire Serial
Availability	Available on most OEM and enclosed modem configurations. Some enclosed modems with more limited connectivity (e.g. the S-Series modems) are configured as either Ethernet or serial, so RS-422 is not available if Ethernet is chosen.
Pros	RS-422 is well suited for longer cable runs than RS-232 and provides a robust differential serial interface for command, status, and low-rate data communication.
Cons	The host side needs an RS-422 interface or adapter. The default serial rate is `115200` bps, which is suitable for command and status traffic but not for high-rate PCM streaming.

RS-232 Serial

Availability

Available on most OEM and enclosed modem configurations. Some enclosed modems with more limited connectivity (e.g. the S-Series modems) are configured as either Ethernet or serial, so RS-422 is not available if Ethernet is chosen.

Pros

RS-232 provides a simple full-duplex serial interface using transmit data, receive data, and ground.

This interface is useful for short local connections to host electronics or lab adapters.

Cons

RS-232 is intended for short cable runs. The default serial rate is 115200 bps, which is suitable for command and status traffic but not for high-rate PCM streaming.

TTL 3.3 V UART

Availability

TTL 3.3 V UART
Availability	Available on OEM modem interfaces where exposed. TTL UART is not exposed as a normal user host interface on enclosed modems.
Pros	The TTL 3.3 V UART is a board-level serial interface using transmit data, receive data, and ground at 3.3 V logic levels. This interface is useful for short local connections to embedded host electronics.
Cons	TTL UART is intended for short, board-level connections only. It requires electrical compatibility with 3.3 V logic and is not appropriate for long cable runs. The default serial rate is `115200` bps, which is suitable for command and status traffic but not for high-rate PCM streaming.

Available on OEM modem interfaces where exposed. TTL UART is not exposed as a normal user host interface on enclosed modems.

Pros

The TTL 3.3 V UART is a board-level serial interface using transmit data, receive data, and ground at 3.3 V logic levels.

This interface is useful for short local connections to embedded host electronics.

Cons

TTL UART is intended for short, board-level connections only. It requires electrical compatibility with 3.3 V logic and is not appropriate for long cable runs. The default serial rate is 115200 bps, which is suitable for command and status traffic but not for high-rate PCM streaming.