This week’s EYE ON NPI (video) will take you to Infinity and Beyond, with Infineon PSoC™ 4000T Microcontrollers and the CY8CPROTO-040T eval board specifically designed to get you started with the 4000t series microcontrollers and using the Infineon-neé-Cypress CapSense technology for capacitive touch buttons and slider.
The Infineon PSoC™ 4000T series of microcontrollers are based around the classic Arm Cortex M0+ core, running at 48 MHz and with 64K flash, 8K of SRAM.
So, a great microcontroller for simple products/white goods that don’t need USB or a graphical display, like headphones, rice cookers, tea kettles or electric toothbrushes.
The chip is optimized for capacitive touch sensing, with timers and lots of capsense inputs, but not a ton of other peripherals: there’s only two serial blocks that can be configured as I2C/UART/SPI, and no ADC/DAC or USB or CAN.
As long as your product is intended to be low-cost, and simple, that’s probably just fine!
The real star of the show on these chips is the CapSense peripheral, which has up to 16 inputs – out of 21 GPIO! These can be configured as “CSD-type” self-capacitance sigma-delta buttons or sliders, or as “CSX-type” mutual-capacitance X-Y grids.
Capacitive sensing is great when you want products that react to touch without needing large and breakable tactile switches. For example, touch sensors on headphones can determine when they are inserted into the ear and when a finger is touching the body to pause or adjust volume. Unlike buttons or encoders, there’s no risk of eventual mechanical failure, rending a product useless: with a smooth clean surface you can still provide a full UI with low cost and maintenance.
The Infineon PSoC™ 4000T series comes with the 5th generation of CapSense, which features autonomous DMA function in deep sleep, great responsivity, and moisture resistance.
One downside of classic capacitive touch solutions is false ‘ghost’ triggering or sluggish ‘touch blindness’ when the touch surface is wet. This is a common issue with products that end up being used in a kitchen, bathroom, laundry room, while exercising or outside. That’s because droplets of water have capacitance on the order of the human finger and so each droplet looks like a touch.
Most capacitive sense implementations have a slow self-zeroing drift calibration procedure, but they don’t handle sudden water sprays. CapSense 5th gen, by comparison, will maintain the same raw capacitive count even when there’s spray, mist or droplets!
Another neat feature is the autonomous sensing block, which allows ultra low deep sleep current of 6uA with touch-to-wake. Instead of powering up the whole core to do the capacitive touch reading and averaging in the main process thread, readings are done in a zombie mode so that we only wake up when touches are detected.
If your next product design needs a reliable capacitive touch interface, the CapSense 5th gen-powered Infineon PSoC™ 4000T series is an excellent low-power Cortex M0+ chip that can act as the main processor of your product with high integration for a tiny BOM at an attractive price. You can get started fast by picking up a CY8CPROTO-040T eval board that has a programming/debug interface as well as button, slider and proximity sensing CapSense elements. Order today and your CY8CPROTO will ship immediately, so that you can get started with your development by tomorrow afternoon!
See the video below:
