\u00a0 \u00a0 \u00a0 \u00a0 This past week, I focused on finalizing the capacitive touch design and getting a reliable system in place. Through testing, I realized that the original grid approach was fundamentally flawed due to how the MPR121 sensor operates. Each time the sensor initializes, it sets a default baseline capacitance, which is significantly influenced by any materials in contact with the copper foil tape. Because of this, stacking multiple layers caused major inconsistencies in readings, especially on the bottom layer.
\nTo address this, I shifted the design by offsetting the row and column layers and introduced rubber bands for the top layer. The idea was that the flexibility of the rubber bands would allow touch pressure to bridge the gap between rows and columns without keeping them in constant contact. However, the rubber bands proved to be too insulating for a finger to trigger a reliable capacitance change.
\nTo solve this, I wrapped each of the 81 intersection points with small patches of copper foil tape. This modification made a significant difference and resolved the detection issue, enabling consistent touch registration.
\nAt this stage, the system only needs some threshold tuning and full integration. My upcoming goals include finalizing the enclosure to house all components cleanly and completing integration with the software side. While there is still work to be done to ensure the system is fully functional, accurate, and cohesive, I\u2019m confident that we are on track to finish before the final demo.<\/p>\n","protected":false},"excerpt":{"rendered":"
\u00a0 \u00a0 \u00a0 \u00a0 This past week, I focused on finalizing the capacitive touch design and getting a reliable system in place. Through testing, I realized that the original grid approach was fundamentally flawed due to how the MPR121 sensor operates. Each time the sensor initializes, it sets a default baseline capacitance, which is significantly … <\/p>\n