2 Hardware - AWS IoT ExpressLink
2.1 Block diagram2.2 Pin definitions

2 Hardware

An AWS IoT ExpressLink qualified module is generally composed of the following elements: (see block diagram)

  • a module processor (MCU), that handles the AT command parser and manages the network connectivity protocols (ethernet, Wi-Fi, cellular)

  • a minimum of six I/Os

  • a pre-provisioned secure element or equivalent secure enclave that provides crypto hardware acceleration, random number generation and secure key storage

  • a non-volatile memory that provides bulk storage sufficient to support the module's own over-the-air updates (OTA) and host processor OTA (HOTA)

2.1 Block diagram

Figure 1 - Simplified block diagram

Figure 1 - Simplified block diagram

2.2 Pin definitions

2.2.1   GND (input) – Ground

2.2.2   VCC (input) – 3.3v

2.2.3   TXD (output) – Serial interface Universal Asynchronous Receiver the Transmitter (UART) TX from module

UART output to the host processor/application processor.

2.2.4   RXD (input) – Serial interface Universal Asynchronous Receiver the Transmitter (UART) RX to module

UART input to the ExpressLink, from the host processor/application processor.

2.2.5   RST (input) – holds module in reset

When asserted (low), the ExpressLink module is held in reset (low power, disconnected, all queues emptied and error conditions cleared).

2.2.6   WAKE (input) – low-power sleep mode wakeup

When not asserted (high), the ExpressLink module is allowed to enter a low power sleep mode. If in low power sleep mode and asserted (low), this will awake the ExpressLink module.

2.2.7   Event (output) – Asynchronous Event Flag

When asserted, the ExpressLink module indicates to the host processor that an event has occurred (disconnect error or message received on a subscribed topic) and a notification is available in the event queue waiting to be delivered. It is de-asserted when the event queue is emptied. A host processor can connect an interrupt input to this signal (rising edge) or can poll the event queue at regular intervals (see 7.2.1 EVENT?   »Request the next event in the queue«).