Watch App Design

Winning strategies for wearables. If you’re considering a move into wearables, here are a few recommendations:

  • Tech fit for the real world – Consider how to best marry amazing technical capabilities with people’s real-world habits and desires.
  • Understand needs – Ensure you know who you’re designing the wearables for, and what their needs and desires are.
  • Sharp focus – Prioritize ruthlessly around your core service and its core benefit, your wearable device will inevitably die if it contracts featuritis.
  • Segment functionality – As wearables should be small, carefully consider what’s best done and seen on the device itself, and what can be “delegated” to a smartphone.
  • Make the experience desirable and stylish – As Bill Geiser of MetaWatch says, “we carry devices but we wear fashion.”
  • Know the data core – Obsess about the hardware, but obsess even more about the smart data service enabled by the technology. The gadget is merely the keyhole into a kingdom of interconnected data.
  • Data fluidity – Allow users’ data to move fluidly between devices and be freely exported and aggregated, as users will get more benefit from solutions that can be compared and mashed up.
  • Design for the glance – Ensure a simple glance at the device can provide information and value.
  • Have fun inventing – The category needs leadership. Follow the advice of legendary inventor and designer Buckminster Fuller, who said “The best way to predict the future is to design it.”
  • _________________________________
  • Elegance and simplicity are core attributes of the quarter-sized activity tracker Misfit Shine, yet it can be used flexibly for several different activities and situations.
  • Scales by Withings piggyback cleverly on an existing daily ritual – weighing oneself – rather than trying to introduce completely new digital rituals.
  • The Fjord-designed smartphone app Macaw aggregates data from several sources in one experience, allowing users to get an overview of various things they track.
  • Category pioneers FitBit have long been known for reliable and accurate data, which is a foundation for trust.
  • Excellent design drivers around glanceability and “hands freedom” guide smart watch pioneers MetaWatch.

ESP32 Sample Service

        // SampleBuffferInitI2S
	// Do the initial setup required if we're going to capture the audio with I2S

	//i2s number
	#define EXAMPLE_I2S_NUM           (I2S_NUM_0)
	//i2s sample rate
	//enable display buffer for debug
	#define EXAMPLE_I2S_BUF_DEBUG     (0)
	//I2S read buffer length
	//I2S built-in ADC unit
	#define I2S_ADC_UNIT              ADC_UNIT_1
	//I2S built-in ADC channel
	#define I2S_ADC_CHANNEL           ADC1_CHANNEL_0

	//flash record size, for recording 5 second
	void SampleBufferInitI2S()
		i2s_config_t i2s_config;
		i2s_config.mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_RX | I2S_MODE_ADC_BUILT_IN);
    	        i2s_config.sample_rate = SAMPLING_FREQUENCY;            
    	        i2s_config.dma_buf_len = MAX_SAMPLES;                   
    	        i2s_config.bits_per_sample = I2S_BITS_PER_SAMPLE_16BIT;
    	        i2s_config.channel_format = I2S_CHANNEL_FMT_ONLY_LEFT;  
    	        i2s_config.use_apll = false,
    	        i2s_config.communication_format = I2S_COMM_FORMAT_I2S_MSB;
    	        i2s_config.intr_alloc_flags = ESP_INTR_FLAG_LEVEL1;
    	        i2s_config.dma_buf_count = 2;

		//install and start i2s driver

		ESP_ERROR_CHECK( adc_gpio_init(ADC_UNIT_1, ADC_CHANNEL_0) );
		ESP_ERROR_CHECK( i2s_driver_install(EXAMPLE_I2S_NUM, &i2s_config,  0, NULL) );
		ESP_ERROR_CHECK( i2s_set_adc_mode(I2S_ADC_UNIT, I2S_ADC_CHANNEL) );		


	void FillBufferI2S()
		uint16_t byteBuffer[MAX_SAMPLES];

		if (IsBufferFull())
			Serial.printf("BUG: FillBUfferI2S found buffer already full.");
		size_t bytesRead = 0;
    	        ESP_ERROR_CHECK( i2s_adc_enable(EXAMPLE_I2S_NUM) );
                ESP_ERROR_CHECK( i2s_read(EXAMPLE_I2S_NUM, (void*) byteBuffer, sizeof(byteBuffer), &bytesRead, portMAX_DELAY) );
	        ESP_ERROR_CHECK( i2s_adc_disable(EXAMPLE_I2S_NUM) );

		_cSamples = _MaxSamples;
		if (bytesRead != sizeof(byteBuffer))
			Serial.printf("Could only read %u byttes of %u in FillBufferI2S()\n", bytesRead, sizeof(byteBuffer));

		for (int i = 0; i < ARRAYSIZE(byteBuffer); i++)
			_vReal[i] = byteBuffer[i];

		//for (int i = 0; i < 128; i++)
		//	Serial.printf("%d, %f\n", i, _vReal[i]);

		_cSamples = MAX_SAMPLES;


Need to try this (from Reddit): ADC configured as an I2S peripheral that writes directly to system memory (DMA).


nRF52840 SoC

High-end nRF52 Series multiprotocol SoC for high-performance, feature-rich applications with best-in-class security.

64 MHz Cortex-M4F
1 MB Flash, 256 KB RAM
2.4 GHz Transceiver
2 Mbps, 1 Mbps, Long Range
Bluetooth 5, Bluetooth mesh
ANT, 802.15.4, Thread, Zigbee
+8 dBm TX Power
128-bit AES CCM, ARM CryptoCell
12-bit ADC
USB 2.0