Firmware Developer

We have a contract opportunity for a ESP32-C3-MINI-2U Firmware developer to enable a Wifi connection to a Wifi router to transmit emails/texts, etc...

We require a PCB design for fabrication. The device is based on an Espressif ESP32C3 microcontroller that utilizes a 2.4Ghz IEEE 802.11 b/g/n-compliant WiFi transmitter to send SMS messages via an internet connected router to an end user.

The PCB will be replacing an existing design so therefore has specific requirements for the PCB layout and component placement to facilitate the use of an existing enclosure. The PCB is expected to require four layers. Recommended design practices for the ESP32C3 will be provided as well as a drawing specifying the location of certain components. 

Project Details:

Hardware

Devices are mounted on a pre-fabricated, pre-assembled circuit board.

Microcontroller - ESP32-C3-MINI-2U

NOTE: The firmware must be proven to run on an ESP32-C3 microcontroller

The actual part is an ESP32-C3-MINI 2U with an external antenna. Note that the ESP32-C3 has limited Deep Sleep functions compared to some other ESP32 MCUs. Developing the firmware on a device other than the ESP32-C3 may not function correctly and would not be acceptable.

Inputs/Outputs

The ESP32-C3-MINI-2U (ESP32) is interfaced to a PIC16F1503 microcontroller (PIC). The ESP32 receives 3 digital output signals from the PIC as digital inputs on GPIO pins 1,2 & 3.

The PIC, due to its extremely low power requirements, is used to control audible and visual signals via a single LED and piezo buzzer. The PIC’s digital inputs are connected to a magnetically actuated reed switch and push button switch. It also monitors the battery voltage and outputs a digital signal if the battery voltage falls below 6 VDC. Due to its high power consumption (other than Deep Sleep Mode), the ESP32’s only function is to send email/text message notifications regarding battery status and alarm events.Power source is a 9VDC rectangular battery. Battery life is of primary importance. Target battery life is 1 year under normal operating conditions.

Firmware Requirements -  ESP32 Only

The ESP32 will wake from Deep Sleep mode upon detecting a logic level HIGH on any one of the inputs and send an SMS text message via email (using WiFi) according to the bit pattern on the inputs.. The WiFi must use Dynamic SSID and Password for connection so the user can enter (via HTML form) their router''s SSID and user password.

The PIC outputs/ESP32 GPIO inputs are encoded in 3-bit binary format as follows:

GPIO 3-2-1 (Dec)    (0 = LOW 1 = HIGH)

          0 0 0 = (0)  Idle State (Deep Sleep Mode - No messages)

          0 0 1 = (1)  Wake Up - Send Welcome! Message (first time power up) -return to Deep Sleep

          0 1 0 = (2)  Wake Up - TEST MODE - Send Email - return to Deep Sleep    

          0 1 1 = (3)  Wake Up - LOW BATTERY WARNING - Send Email - return to DeepSleep

          1 0 0 = (4)  ALARM notification - Send Email - return to Deep Sleep

          1 1 1 = (7)  SETUP MODE (message)

INITIAL SETUP  - When first powered on, the device will display the ESP32 Wifi (named Blackwater) in the available WiFI connections of the user''s computer, tablet or cell phone. The user will select the ESP32 Wifi connection, then open a web page in their device''s browser and enter the address () in the address bar. This opens a web page in WiFi Access Mode to allow entry of the WiFi credentials, store the credentials in EEPROM and then switch to WiFi Station Mode.( ). The web page must have fields to allow entry of the user WiFi SSID, WiFi Password and recipient email and  phone number. The web page must also include a dropdown list of cell carriers with their gateway domains as described here: 

The gateway domain must be appended to the phone number.

The email account will be a gmail account that is determined by you to test the code. I will subsequently modify this email address in the code myself. 

Any subsequent reboot of the device will connect to WiFi using the stored credentials, unless the credentials are changed by entering SETUP Mode.