4 Modes of Operation

The EV98D91A 2-lead µVSFN mikroBUS compatible socket board has multiple modes of operation. These are configured via jumpers or 0Ω resistors.

Power Selection

A user can choose between 3.3V or 5V power from the interface header by installing a 0Ω resistor in either the R3 or the R4 locations. When R3 is installed, the 3.3V power source is connected. When R4 is installed, the 5.0V power source is connected. The board is shipped with a default 3.3V supply. If 5V are required, remove the R3 and install the R4. Prior to enabling 5V operation, ensure that the host micro-controller board is capable of supporting 5V operation.

Important: R3 and R4 must never be populated at the same time.

Modes of Operation

There are two possible modes of operation depending on the SWI selected. For both interfaces, only a parasitically-powered device can be used on the board. The following table indicates how the EV98D91A development board must be configured for each mode.

Table 4-1. Modes of Operation
Interface Type	Jumper Connection	Devices
SWI⁽¹⁾	SIO-RX/TX	n/a
SWI-PWM⁽²⁾	SIO-SIO_2	Security Devices ECC206 – Asymmetric Cryptography SHA106 – Symmetric Cryptogrpahy Memory Devices AT21CS01 – 1 kBit (1.7 to 3.6 V_CC) AT21CS11 – 1 kBit (2.7 to 4.5 V_CC)⁽³⁾

Note:

Currently, there are no CryptoAuthentication devices that are implemented that utilize the SWI in the 2-lead µVSFN package.
Additional devices may be released at a future date.
Check with Microchip to determine the availability of this device in the 2-lead µVSFN package.

The SWI mode uses the RX/TX signal for communication purposes. Note that the RX/TX signals are shorted together on the development board. A pull-up resistor is used to pull the signal High when the crypto device communicates to the microcontroller. There is a 1-kΩ pull-up resistor R2 connected to the TX/RX signals. Jumper J3 needs to short the RX/TX signal and SIO pins.

The SWI-PWM mode uses the PWM signal for communication. The single-wire communication will be through SIO_2 using J2 pin 1. There is a 1-kΩ pull-up resistor R5 on SIO_2. Jumper J3 needs to short the SIO_2 and SIO pins.

Parasitic Power

Parasitic power devices do not require a dedicated power source. An internal capacitor provides the decoupling and charge storage that the device needs for proper operation. For correct operation, the SIO signal must always be greater than the minimum supply operating voltage of the device. See the specific device data sheet for more details and recommendations.