Sensors Range Finder

Demonstrates reading data from a range finder connected to a device UART.

• SDK directory: apps/sensors/range_finder

API Features Demonstrated

• Event Handling

  • zn_event_enable_irq_events
  • zn_event_issue

• Peripherals/UART

  • zn_uart_configure
  • zn_uart_peek_bytes
  • zn_uart_receive_bytes
  • zn_uart_register_rx_callback
  • zn_uart_transmit_bytes

Platforms

This app works on:

• AMW004 - Zentri Mackerel evaluation board
• AMW106 - Zentri Moray evaluation board
• AVN4343 - Avnet IoT Starter Kit
• NXP-SCCK - NXP Secure Cloud Connectivity Kit

Requirements and Prerequisites

This app requires a ZentriOS evaluation board. See the Platforms list above.

This app requires a Digilent Pmod MAXSONAR range finder.

Description

This app demonstrates reading range finding data from a Digilent Pmod MAXSONAR, connected to a device UART.

Usage Instructions

Connect the range finder to the device UART.

Open a ZentriOS serial terminal to the device. See Getting Started, Opening a ZentriOS Terminal.

Run the app.

The app displays range finder data on the terminal.

Implementation

main.c

zn_app_init

• Calls zn_event_enable_irq_events to allow UART interrupt events
• Calls initialize_uart to set up the UART

initialize_uart

• Sets up a UART config for 9600 baud, width 8 bits, no parity, 1 stop bit and no flow control.
• Calls zn_uart_configure to configure the UART with the config.
• Calls zn_uart_register_rx_callback to set up the UART rx callback function as uart_rx_irq_callback

uart_rx_irq_callback

• Calls zn_event_issue to fire off the uart_rx_event_handler. This is necessary to move processing out of the hardware IRQ context of uart_rx_irq_callback and back into the ZAP context of uart_rx_event_handler. See Development, Execution Content.

uart_rx_event_handler

• Calls zn_uart_peek_bytes to check for available data
• Loops, calling zn_uart_receive_bytes to receive a byte at a time, until byte is R character
• Calls zn_uart_receive_bytes to receive integer range value as 3 ASCII digits.
• Displays range value if in range, or an out of range notification.
• Displays result on terminal.

Source

See:

• main.c