1. Introduction
HELLO-STEM-UNO-R3-LB is a compatible Arduino UNO R3 ATmega328P development board, upgrading the traditional USB-B to Type-C interface;CH340K implements USB to serial port; TPS54302DDCR implements wide voltage VIN input step-down 5V; SLM6800 as dual-cell lithium battery step-up charging management chip, supports 7.4V (2S) lithium battery charging and discharging;VIN interface is reusable, it can be used as a 7.4V lithium battery interface as well as an external DC power input port, and can be connected to external VIN power when the battery is not connected.Supports USB power supply, external VIN DC power supply, and 7.4V two-cell lithium battery power supply in three power supply modes; toggle switch to manually switch between VUSB and VBAT power supply;The pin is 100% compatible with the UNO R3 expansion board, aimed at maker education, portable prototype development, and microcontroller experimental projects.
2, Technical Specifications
Main Control MCU | ATMEGA328P-AU |
|---|---|
Flash | 32KB (Bootloader occupies 0.5KB) |
SRAM | 2KB |
EEPROM | 1KB |
System Clock | 16 MHz ceramic resonator |
Main Control Working Voltage | 5V; IO voltage withstand 5V; peripherals 3.3V |
Digital IO | D0-D13, a total of 14 channels; D3/D5/D6/D9/D10/D11 support PWM; single IO maximum 20mA sink / source current |
Analog input | A0-A7, a total of 8 ADC channels, 10-bit resolution |
Communication interface | UART(D0-D1), I2C(A4-A5), SPI(D11/D12/D13) |
USB to serial port | CH340K |
5V step-down chip | TPS54302DDCR; Input 4.5-28V, output 5V, continuous 3A; 400kHz synchronous Buck, built-in protection; Enabled by toggle switch |
Lithium battery charging chip | SLM6800;5V input step-up charge 2S lithium battery (nominal 7.4V, fully charged 8.4V); Maximum charging current 1A; Switching frequency 750kHz; Charging voltage accuracy ยฑ1%; Overcharge, short-circuit, over-temperature protection |
3.3V voltage regulation | AMS1117-3.3, maximum output 800mA |
Power supply input | Type-C 5V; VIN multiplex interface: Can accept 6-9V DC external power, or can accept 7.4V (2 series lithium polymer, fully charged 8.4V) lithium battery;Do not connect external power and lithium battery at the same time |
Power switching device | Toggle switch, choose one: VUSB power / VBAT power, simultaneously controlling TPS54302DDCR enable and system 5V power path |
โ ๏ธImportant: VIN is a multiplex interface, when connected to the battery, only the connection is allowed2 series lithium batteries (nominal 7.4V)Prohibit single battery 3.7V and 3 series or more lithium batteries; It is recommended to use 6-9V for long-term use when VIN is used as an external power input;Prohibit simultaneous connection of external power and lithium batteries to the VIN interface.
3, Features
1. Main controller: ATMEGA328P-AU, 16MHz external ceramic resonator
2. USB interface: Type-C, CH340K USB-UART bridge, for program download and serial communication.
3. Power supply mode: Type-C USB5V; VIN interface multiplexing: External DC 6-9V input / 7.4V (2S) lithium battery connection; toggle switch to manually switch VUSB/VBAT power supply.
4. Power output: TPS54302DDCR outputs 5V; AMS1117-3.3 outputs 3.3V.
5. Battery management: SLM6800, 5V input step-up to charge 2S lithium battery, cutoff at full charge 8.4V, maximum charging current 1A.
6. IO Resources: 14 digital IO (6 PWM channels), 8 analog inputs A0-A7; UART/I2C/SPI hardware peripherals.
7. Peripherals: Reset button, power, TX/RX, D13 user LED, ICSP programming interface,VUSB/VBAT power toggle switch.
8. Fully compatible with standard Arduino UNO R3 expansion board.
4, Circuit Board Size
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5, Development board decoding
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โ Reset key
Press the reset button and run the program again.โกUSB serial chip
This chip is responsible for converting the data received from USB into serial data for the main control chip.To be updated.......
Notice
1.IO pin maximum sink/source current is 20mA, high-power peripherals must be driven by external circuits (MOS, transistor, relay module).
2. A6, A7 only support analog input, cannot be used as digital IO.
3. SLM6800 is only compatible with.2 in series 7.4V lithium battery (fully charged 8.4V).Prohibition of single battery or 3 in series lithium battery connection, otherwise battery overcharge fire and chip burnout.
4. The input voltage of VIN must not exceed 18V, it is recommended to โค6-9V as an external power input for a long time.
5. VIN connects to the lithium battery and requires strict distinction between V+(B+) and G-(B-). Reverse connection will directly damage the SLM6800.
6. Toggle switch function:VUSBGear off TPS54302DDCR, USB directly supplies 5V power to the mainboard;VBATGear on TPS54302DDCR, 5V is output by TPS54302DDCR to the mainboard, cutting off power supply from USB to the mainboard, USB retains data and charging input functions.
7. The switch is set to the VBAT position, there is no valid power at the VIN interface, only insert Type-C, the mainboard will not start, and Type-C only performs charging and data communication.
8. VIN is a multiplexed interface,It is strictly prohibited to connect external DC power and lithium batteries simultaneously to the VIN interface, which will cause hardware damage.
6. Special Lithium Battery Interface
Special battery interface, can be connected with 18650 lithium batteries, it is easier to layout when creating mobile projects.
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7, sensor and expansion accessories interface
The on-board digital G|V|S interface is more convenient and quick to connect sensors or actuators, and no expansion board is needed when building projects.
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