How Does The ADC 21 Click Board™ Work?
The ADC 21 Click Board™ is based on the ADC1283, a high-performance eight-channel analogue-to-digital converter from STMicroelectronics. The ADC1283 implements a successive approximation register (SAR) structure to convert analogue signals into 12-bit pure binary digital outputs. The conversion circuit includes a fast settling time comparator to convey instruction into the register to store digital 0 or 1 and a redistribution DAC with logic control to have the ADC compare the track signal with a reference signal at each clock cycle.
The ADC 21 Click Board™ communicates with MCU through a standard SPI interface and operates at clock rates up to 3.2MHz, for all configurations and acquiring conversion results. The AD conversion is carried out in two phases. The sampling phase conveys the input signal through the capacitance array for the first three clock cycles. Then, the evaluation phase converts into a digital 12-bit signal within 13 clock cycles. At each clock cycle of the evaluation phase, the hold signal is compared with a new value distributed by the DAC, and the result is stored in the 12-bit register, with MSB first. A complete conversion requires 16 clock cycles to generate a new 12-bit word on the SDO pin on the mikroBUS™ socket.
This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC SEL jumper. This way, it is allowed for both 3.3V and 5V capable MCUs to use the communication lines properly. Additionally, there is a possibility for the ADC1283 analogue power supply selection via jumper labelled AVCC SEL to supply the ADC1283 from an external power supply in the range from 2.7V to 5.5V or with mikroBUS™ power rails. However, the ADC 21 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.
SPECIFICATIONS
| Type | ADC |
| Applications | It can be used for the most demanding applications, from general-purpose remote data acquisition and instrumentation to industrial applications |
| On-board modules | ADC1283 - eight-channel analog-to-digital converter from STMicroelectronics |
| Key Features | Low power consumption, high accuracy, high-speed serial interface, high performance, selectable conversion rate, 12-bit SAR-based ADC, selectable analogue power supply, and more |
| Interface | SPI |
| Compatibility | mikroBUS |
| Click board size | M (42.9 x 25.4 mm) |
| Input Voltage | 3.3V or 5V |
PINOUT DIAGRAM
This table shows how the pinout of the ADC 21 Click Board™ corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).
| Notes | Pin | Pin | Notes | ||||
|---|---|---|---|---|---|---|---|
| NC | 1 | AN | PWM | 16 | NC | ||
| NC | 2 | RST | INT | 15 | NC | ||
| SPI Chip Select | CS | 3 | CS | RX | 14 | NC | |
| SPI Clock | SCK | 4 | SCK | TX | 13 | NC | |
| SPI Data OUT | SDO | 5 | MISO | SCL | 12 | NC | |
| SPI Data IN | SDI | 6 | MOSI | SDA | 11 | NC | |
| Power Supply | 3.3V | 7 | 3.3V | 5V | 10 | 5V | Power Supply |
| Ground | GND | 8 | GND | GND | 9 | GND | Ground |
ONBOARD SETTINGS AND INDICATORS
| Label | Name | Default | Description |
|---|---|---|---|
| LD1 | PWR | - | Power LED Indicator |
| JP1 | VCC SEL | Left | Logic Level Voltage Selection 3V3/5V: Left position 3V3, Right position 5V |
| JP2 | AVCC SEL | Left | Analog Power Supply Selection VCC/VEXT: Left position VCC, Right position VEXT |
| J1 | - | Populated | Analog Input Channels Header |
ADC 21 CLICK ELECTRICAL SPECIFICATIONS
| Description | Min | Typ | Max | Unit |
|---|---|---|---|---|
| Supply Voltage | 3.3 | - | 5 | V |
| Analog Power Supply Voltage | 2.7 | - | 5.5 | V |
| Resolution | - | 12 | - | bits |
| Data Rate | 50 | - | 200 | ksps |