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As of 2025-07-24

Handling Special Pins

Describes pins with special behavior in TWELITE.

1: Handling Special Pins (TWELITE BLUE / RED)

1 - Handling Special Pins (TWELITE BLUE / RED)

Explanation of pins with special behavior in TWELITE BLUE / RED

SPIMISO (also known as DO1, Extremely Simple! Standard App name: PWM3)

This pin is often used as an output pin, but during module power-up or reset, it behaves as an input pin. If the voltage level is detected as Low at that time, the module will start up in programming mode.

Please pay attention to the voltage at startup on this pin.

In the case of the Extremely Simple! Standard App (PWM3 — resistor — LED — GND), an undefined voltage near GND will be present at startup. It is recommended to make all PWM ports (VCC — resistor — LED — PWM?) and set the option bit (00010000, which inverts the PWM waveform).

SPICLK (also known as DO0, Extremely Simple! Standard App name: PWM2)

This pin is used as an output. It has been reported that applying intermediate voltage from external sources (even with some output impedance) can cause the TWE module not to transition into programming mode.

When connecting LEDs or transistors, the pin may be in an intermediate state at startup or during sleep recovery, which can cause malfunction. It is recommended to use either an unconnected state or a circuit configuration with a pull-up to Vcc.

DIO0 (also known as ADC3), DIO1 (also known as ADC4)

These pins are shared with analog inputs. As a firmware consideration, internal pull-ups must be disabled during AD conversion.

ADC2 (also known as Vref)

ADC2 can be used as an input for the reference voltage. Software implementation is required for its use.

Note that there is no pin that outputs the reference voltage .

GND Pins

For the SMD version, it is recommended to connect pins 28, 30-32 to GND, but operation without connection is also possible. Even when unconnected, no significant change in wireless performance has been observed.