Data Sheet

casambi.com
4
3. System blocks
3.1 General Purpose I/O (GPIO)
The CBM-003B/C has 12 General Purpose I/O pins.
Some of them are High-drive (9 mA) while some are
standard-drive (2 mA). Each GPIO can be accessed
individually, and each has the following features:
• Input/output direction
• Configurable output drive strength,
standard-drive (6 pcs) or High-drive (6 pcs)
• Configurable internal pull-up and pull-down resistors
• Buffered inputs
• Trigger interrupt on all pins (rising edge,
falling edge, any change)
• Serial interface output can be freely configured
to any of 6 High-drive pins
• >10 kHz PWM output can be freely configured
to any of 6 High-drive pins
• ≤10 kHz PWM output can be freely configured
to any of 12 GPIO pins
GPIO pins 0-3 also support analog input signals when
an internal Analog-to-Digital Converter (ADC) is used.
3.2 Analog-to-Digital Converter (ADC)
The Casambi system can use an Analog-to-Digital
Converter (ADC), for example, in light level sensing
and battery voltage monitoring. The ADC resolution is
selected automatically (8-bit or 12-bit) based on the
application. The specific functionality available through
the ADC inputs is determined by Casambi Firmware
and how it is configured.
The Analog-to-Digital Voltage range for any ADC input
is 0-3.6 V, but not above Vcc. This means that 0 V
gives a zero reading from the ADC, and 3.6 V gives
a maximum reading (255 for 8-bit and 4095 for 12-bit
resolution).
No pin should be exposed to voltages higher than
VCC. The operating voltage of the module, VCC, is the
maximum limit to the analog input voltage. While the full
range of ADC is 3.6V, if the supply voltage Vcc is only
3.3V or 3.0V, the full range cannot be used.
3.3 PWM Output
Any GPIO pin can be configured to output a PWM
signal, and up to 8 PWM channels can be used
simultaneously. A PWM frequency can be determined
freely up to 40 kHz and is the same with all PWM
channels. However, any PWM over 10 kHz requires the
use of High-drive pin. The resolution can be selected
between 100-5000 steps. The maximum resolution
depends on the PWM frequency.
The PWM signal is logic level (max. VCC), and it has
a driving capacity of 2 mA (standard) or 9 mA on
a High-drive pin. See also the Nordic nRF52840
datasheet for limitations. An adjustable analog voltage
(0 V - VCC) can be derived from the PWM signal
by an external RC filter.
Picture 2 Adjustable 0–10V output from PWM signal
CBM-002A/B
2,2 μF
GPIOx
10kΩ
10 kHz PWM 0-3V analog
+3 VDC
G3,33 0-10V
output
CBM-003B/C