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로드셀 앰프 -AD7780 모듈
(LOAD CELL 5 CLICK)
개요
- 본 제품은 로드셀 앰프 -AD7780 모듈입니다.
- 프로그래밍 가능 저전력 24비트 ADC AD7780 칩을 탑재한 제품으로 로드셀과 직접 인터페이스하여 사용이 가능합니다.
- SPI 인터페이스를 깆고 있으며, 점퍼를 통해 3.3V/5V 를 선택하여 사용이 가능합니다.
특징
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Type Force Applications Can be used for safety-critical and weight measurement applications. On-board modules AD7780 - pin-programmable, low power, 24-bit sigma-delta ΣΔ ADC from Analog Devices Key Features Low power consumption, pin-programmable filter response, pin-programmable reset and gain, internal bridge power-down switch, independent interface power supply, and more. Interface SPI Compatibility mikroBUS Click board size M (42.9 x 25.4 mm) -
Load Cell 5 Click as its foundation uses the AD7780, a pin programmable, low power, low drift 24-bit ΣΔ ADC from Analog Devices, that includes a PGA and uses an internal clock. The AD7780 typically consumes only 330μA and simplifies this weigh scale design since most of the system building blocks are already on the chip. The AD7780 has two filter options selectable via FIL pin(low state - the 16.7Hz, high state - 10Hz) and a Power-Down Mode allowing the user to switch off the power to the bridge sensor and power-down the AD7780 when not converting, increasing the battery life.
Since the AD7780 provides an integrated solution for weighing scales, it interfaces directly to the load cell. The only required external components, which are also on the Click board™, are filters on the analog inputs and capacitors on the reference pins for EMC purposes. The low-level signal from the load cell is amplified by the AD7780's internal PGA programmed via the PWM pin of the mikroBUS™ socket, labeled as GN, to operate with a gain of 128 or 1. The conversions from the AD7780 are then sent to the MCU through SPI serial interface, where the digital information is converted to weight.
This Click board™ uses the 6-wire load cell configuration, which has two sense pins, ground, power supply, and two output connections. The load cell differential SENSE lines connected to the AD7780 reference inputs create a ratiometric configuration immune to low-frequency changes in the power supply excitation voltage. Those sense pins are connected to the high and low sides of the Wheatstone bridge, where voltage can be accurately measured, regardless of the voltage drop due to the wiring resistance.
The AD7780 has separate analog and digital power supply pins. The analog and digital power supplies are independent of each other to be different, or the same, potentials achieved with the AVDD SEL jumper. This feature allows selecting the AD7780 power supply between an external power supply (2.7 - 5.25V) and logic voltage levels supplied via mikroBUS™ rails.
Load Cell 5 Click communicates with MCU using a standard SPI interface with a dual-purpose DOUT/RDY line. This line can function as a regular data output pin for the SPI interface or as a data ready pin (interrupt) labeled as RDY and routed on the INT pin of the mikroBUS socket. Also, it uses the RST pin on the mikroBUS™ socket, which performs the Hardware Reset function by putting this pin in a logic low state, and a blue diode labeled as ACTIVE used to indicate the device's Active Operational Status.
This Click board™ can operate with both 3.3V and 5V logic voltage levels selected via the VCC SEL jumper. This way, it is allowed for both 3.3V and 5V capable MCUs to properly use the I2C communication lines. However, the Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used, as a reference, for further development
