Autonomous on-Chip Debugging for Sensors Based on AVR Microcontrollers

Abstract

Sensors are often based on minimalistic microcontrollers for their reduced power consumption and size. Because of the specific hardware of sensors, their software development, including debugging, is also particular. Simulators and external computers are conventional approaches to sensor debugging, but they both face limitations such as the supported hardware and debugging conditions. In this paper, we propose a fully autonomous on-chip debugging solution for sensors (and other devices) based on AVR microcontrollers, with a particular focus on human-machine interaction. The proposal is then validated in practice through various experiments, notably involving real-world sensors. Formal measurement of the induced overhead is also conducted, which eventually demonstrates the applicability of the proposal.

Memory Optimisation on AVR Microcontrollers for IoT Devices’ Minimalistic Displays

“…The selected 1.8 in TFT-LCD panel features an 18-bit colour depth, which is common for such low-specification TFT-LCDs. In other words, the colour of one single pixel is expressed with eight bits, and there are in total 2 18 = 262,144 available colours. The resolution of the display is 128 × 160 pixels, with thus a total of 20,480 pixels.…”

“…The HEX file has then been conventionally transferred to the microcontroller with the avrdude utility (see, for instance, ref. [18] for additional details). The size of the generated machine code has been calculated with avr-size of GNU size, also from the GNU Binutils collection.…”

“…Because of power consumption (battery) and cost issues, the hardware of such devices is minimalistic [2]. This is especially the case when they are based on microcontrollers: very few memory is available, and interfacing is reduced to a minimum.…”

“…Displays for such minimalistic devices are often either a text-only liquid crystal display (LCD) panel that is only capable of displaying hard-coded characters (e.g., displays based on the Hitachi driver HD44780 [3]), very small thin-film transistor-LCD (TFT-LCD) panels (e.g., 18-bit colour TFT-LCD panels based on the Sitronix driver ST7735R [4], like the Adafruit 0.96 in, 1.44 in and 1.8 in ones) or electronic paper (e.g., WaveShare devices, like [5]). Text-only displays with hard-coded characters do not face memory issues as only character codes, like ASCII codes, need to be transferred to the peripheral.…”