List of CLAsses

The CLA byte of the Direct Protocol selects a family of INStructions.

CLAss Name Cmd/Rsp Interrupt Description
00 PROTOCOL yes yes (limited) Instructions in this class are intended to retrieve the device's meta-data, start/stop the device or change its runlevel or operation mode, establish and manage a secure channel. It is also used by the device to report a protocol error during communication and for time-extensions.
This is more or less the counterpart of the control endpoint (EP0) on USB.
58 CONTROL yes no Instructions in this class are intented to control the device without impacting its current runlevel or operation mode. This can be:
- Driving the UI (light / sound),
- Writing into the non-volatile memory, reading the statistics,
- Accessing the device's I2C bus or other peripherals.
59 ATCRYPTO yes no Instructions in this class gives a direct access to the MicroChip ATECC or ATAES Secure Element, if the device has one.
5A SAM AV yes no Instructions in this class gives a direct access to the NXP SAM AV2 or SAM AV3 Secure Element, if the device has one.
5B READER no yes When the device is configured for Smart Reader Operation, the tokens read from the tags are transmitted to the host using this CLAss on the InterruptIn endpoint. Optionaly, the BulkOut/BulkIn endpoints may convey direct commands to the reader or to the tag.
5D DFU yes no Commands in this class are intended to perform a firmware upgrade. The bootloader is likelly to use them to rewrite the CPU's flash directly, while the standard firmware uses an external memory to store the firmware that will be rewritten upon next startup.
5E ECHO yes no Using this class, the buffer is simply echoed. Only bit 7 of the PCB ('way') is toggled.