Requirements:

• Digilent Nexys A7 (artix7 100T) board
• ESP-C3-Expresslink-Devkit
• 3x USB2microUSB cables
• Digilent HS2 connector
• 3x jumper cables
• PMOD header male-male, 2 rows
• latest version of the FPGA bitfile, which can be found here

Note: I had to manually bend one row of pins in the PMOD header.

CORE-V-SDK:

• download the latest version of the CORE-V-SDK from the official download page and install it
  • the core-v-mcu-cli-test page offers a nice guide: just remember to use the demo project instead of the cli-test project

ESP setup:

• this page provides useful information about how to setup the ESP board
• the ESP is expected to communicate to OpenHW's AWS IoT Core: make sure your ESP has been registered by asking OpenHW's team
• the ESP must have WiFi access; the userguide mentioned above explains how to do it; the relevant commands are also in the iot_task.c file (at_set_wifi() function), but are commented out
  • to enable the configuration of the WiFi interface
    • there must be an active UART connection with the board
    • press a key when requested
    • the ESP module goes in configuration mode and the ESP BLE must be used to provide the WiFi credentials
  • once the configuration is done, do a power cycle: this is necessary to switch off the ESP module, to bring it out of configuration mode
• the same function allows to configure the correct Endpoint: ask OpenHW's team the address of the actual endpoint

Board connections

• host PC to Nexys board (J6)
• host PC to HS2 to Nexys board (JB connector, lower row)
• host PC to ESP board
• Nexys JB.2 to ESP J13.RX
• Nexys JB.3 to ESP J13.TX
• Nexys JB.5 to ESP J13.GND

Identify the USB ports on the host PC The host PC should see 3 /dev/ttyUSB* interfaces:

1. one used for the debugger
2. one used by the MCU to send messages via CLI_print (over UART0)
3. one used by the ESP board to send debug information

Connect via minicom (or similar) to each of the /dev/ttyUSB* device to identify them. After reset:

1. prints no information
2. prints A2 boot
3. prints the ESP bootlog

Running the demo:

1. power up both boards (remember: SW0 must be switched towards the inside of the board, otherwise it is not possible to connect the debugger)
2. [optional] open 2 terminals to see the debug messages
3. open CORE-V-SDK and load the cli-test project (iot_demo branch)
4. compile the code
5. load the executable in the MCU
6. run

An OpenHW Group Grafana dashboard displays the measurements sent to the OpenHW's AWS IoT Core. Contact the OpenHW Staff to obtain the viewer's credentials.