Karyni Hardware Documentation

Karyni is an Open-Source ESP32 Development Board with Stackable Expansion Modules

Documentation

Pin Layout and Functions
On-board Peripherals
- BME280 – Temperature, Pressure, Humidity Sensor with Altimeter
- BMC150 – IMU with e-Compass
- Micro SD Card Holder
- RGB LED
- Buttons
- CP2102 – USB-UART Bridge

Power Supply
- FAN49100 – Buck / Boost Voltage Regulator
- MCP73832 – 500mA Li-Ion Battery Charger
- Power-Path
- Power Consumption Profile
Re-configurable Jumpers
- I2C
- UART
- RGB LED
- Battery Voltage Sense
Open Source

Pin Layout and functions

Karyni Core Board follows a pin layout very similar to that of NodeMCU boards, making it an easy replacement for projects designed around NodeMCU

The pin layout and functions are provided in the chart below, and downloadable as spreadsheet and PDF.

ON-BOARD PERIPHERALS

BME280 – Temperature, Pressure, and Humidity Sensor

BME280 from Bosch Sensortec is a high accuracy environmental sensor.

Applications-

– Warning system for temperature / humidity etc.

– Home automation control

– Heating, ventilation, air conditioning (HVAC) control

– GPS enhancement (TTFF improvement, dead reckoning, slope detection)

– Indoor & outdoor navigation (altitude based on pressure)

– Weather monitoring & forecast

BMC150 – IMU with eCompass

BMC150 from Bosch Sensortec is an e-Compass with 3-axis geomagnetic sensor and 3-axis accelerometer.

Applications –

– Compass for map rotation, navigation, augmented reality

– 6-axis orientation for gaming

– Fall, tap, double-tap detection

– Orientation sensing

Micro SD Card Holder

Karyni Core Board features a micro SD card holder for a detachable external storage.

Example program for using micro SD card with Karyni.

Buttons

Karyni Core Board has two buttons, labelled ‘Reset’ and ‘Boot’ respectiviely, as shown in the image.

Reset button resets the ESP32 SoC.

Boot button is connected to GPIO0. It is used by the ESP32 SoC to detect boot mode during startup. If it is held down during startup, the ESP32 enters into Serial program upload mode.

Boot button can be used as a general purpose button after the startup procedure is finished. See example.

RGB LED

There is a high intensity ASMB-MTB1-0A3A2 RGB LED on board with a diffused lense.

Example program for fading colors on the RGB LED.

CP2102N – USB-UART Bridge

Silicon Labs CP2102N provides USB connectivity to the Karyni Core Board. It uses a similar circuit to NodeMCU boards to automatically reset and select correct boot mode while uploading a firmware through USB.

The CP2102N IC is disconnected from power supply when USB power is not present. This reduces power consumption while running on battery power.

POWER SUPPLY

FAN49100 – Buck / Boost Voltage Regulator

FAN49100AUC330X on Karyni Core Board supplies a fixed 3.3V regulated voltage over an input range of 2.5V – 5.5V.

It is capable of delivering up to 2.5A output current at 3.6V input, which is the nominal operating voltage of a single cell Li-Ion battery.

With efficiency up to 96% and a low quiscent current of 26uA, the FAN49100 provides extended battery run-time and minimal power loss.

FAN49100 datasheet.

MCP73832 – 500mA Li-Ion Battery Charger

Karyni Core Board provides a Li-Ion battery charger based on Microchip MCP73832. The charging current is limited to 500mA with maximum charging voltage at 4.2V.

The power for charging is derived from the micro USB port, also accessible on VBUS pin close to the charger.

Charging status is provided by red LED ‘D3’ labelled ‘CHG’, located close to the battery connector as shown in the image. LED on indicated charging is in process. LED off may indicate charge complete, no battery, or no source power.

Once terminated, charging is automatically restarted when the battery voltage drops to around 3.9V

Power Path

Schottky diodes D1 & D2 provide a power-path management circuit to automatically select the power source based on voltage level.

If USB power is present and voltage is above that of Li-Ion battery, power is supplied from USB port (or VBUS pin). Otherwise Li-Ion battery power is used, if present.

If USB power is not present, CP2102N USB-UART Bridge is disconnected to reduce power consumption from battery.

Power Profile

The table below provides a reference of power consumed by various components on Karyni Base Board.

ESP-WROOM-32 Module	Deep Sleep with RTC	6.3uA
	Deep Sleep without RTC	4.5uA
BME280	Sleep Mode	0.1uA
	Humidity + Temperature	1.8uA @ 1Hz
	Pressure + Temperature	2.8uA @ 1Hz
	Humidity + Pressure + Temperature	3.6uA @ 1 Hz
BMC150	Sleep Mode	1uA + 1uA
	Accelerometer + Magnetometer	190uA @ 10Hz
CP2102N	USB Disconnected	0mA
	USB Suspended	195uA from USB
	Normal @ 115200 baud	9.5mA from USB
FAN49100	Quiescent Current	24uA
	Efficiency: Vin 3.8V, Iout 600mA	96%
	Efficiency: Vin 3.8V, Iout 100mA	91%
	Efficiency: Vin 3.0V, Iout 75mA	90%

Re-Configurable Jumpers

The pins occupied by the on-board peripherals on Karyni Core Board are re-configurable via NC cuttable jumpers located on the bottom side of the board.

Refer to the images below to find the locations of I2C, UART, RGB LED, and Battery voltage resistor network jumpers.

Default connections are as such:

I2C -> SCL – 21; SDA – 22
UART -> USB TX – RX; USB RX – TX (USB DTR and RTS signals are used to control GPIO0 [Boot] and Reset pins)
RGB LED -> Red – 16; Green – 17; Blue – 18
Battery sense voltage divider -> GPIO34 (divided by 27k/100k resistors) [4.2V on battery => 3.3V on ADC]

In order to change the default configuration from any of these pins, you would need to locate the correct jumper, and then cut the small trace running between the two sides of the jumpers. This will disconnect the pin from the peripheral. To use the peripheral, you would need to connect it to one of the GPIO pins.

On the NC jumpers, the pad closer to the header pin is connected to the GPIO pin on ESP32 SoC, and the oppositte one is connected to the peripheral(s).

Open Source

Karyni Development Ecosystem is licensed with —–.

[Need license specific graphics here]

Feel free to use and modify the resources.

Liability disclaimer???

All source files are available under Karyni GitHub account at http://www.github.com/karyni

Design files for Karyni Core Board:

Schematic (PDF)
Board Layout (PDF)
Bill of Material (XLSX)
Eagle Project (ZIP)
Production files (ZIP)