Refine STSAFE-A110 command response timing

[parmi93]

We are currently working with the STSAFE-A110 secure element and noticed that the response wait times for all commands are set to STSAFEA_EXEC_TIME_DEFAULT (500 ms). In contrast, the STSAFE-A120 uses more fine-grained timing values. Would it be possible to refine the timings for the STSAFE-A110 as well? This would make interactions with the STSAFE-A110 faster and more responsive, particularly since we plan to use STSELib to establish a TLS/SSL connection with MbedTLS.

STSELib/services/stsafea/stsafea_timings.c

Lines 58 to 88 in c196d23

	/* STSAFE_A110 */
	{
	STSAFEA_EXEC_TIME_DEFAULT, /* Echo */
	STSAFEA_EXEC_TIME_DEFAULT, /* Reset */
	STSAFEA_EXEC_TIME_DEFAULT, /* Generate Random */
	STSAFEA_EXEC_TIME_DEFAULT, /* Start Session */
	STSAFEA_EXEC_TIME_DEFAULT, /* Decrement zone counter */
	STSAFEA_EXEC_TIME_DEFAULT, /* Read zone */
	STSAFEA_EXEC_TIME_DEFAULT, /* Update zone */
	STSAFEA_EXEC_TIME_DEFAULT, /* Increment zone counter */
	STSAFEA_EXEC_TIME_DEFAULT, /* Derive LORA key */
	STSAFEA_EXEC_TIME_DEFAULT, /* Generate MAC */
	STSAFEA_EXEC_TIME_DEFAULT, /* Verify MAC */
	STSAFEA_EXEC_TIME_DEFAULT, /* Unwrap issuer envelope */
	STSAFEA_EXEC_TIME_DEFAULT, /* Delete MAC */
	STSAFEA_EXEC_TIME_DEFAULT, /* Hibernate */
	STSAFEA_EXEC_TIME_DEFAULT, /* Wrap Local Envelope */
	STSAFEA_EXEC_TIME_DEFAULT, /* Unwrap Local Envelope */
	STSAFEA_EXEC_TIME_DEFAULT, /* Put attribute */
	STSAFEA_EXEC_TIME_DEFAULT, /* Generate key */
	STSAFEA_EXEC_TIME_DEFAULT, /* Put key */
	STSAFEA_EXEC_TIME_DEFAULT, /* Configure */
	STSAFEA_EXEC_TIME_DEFAULT, /* Query */
	STSAFEA_EXEC_TIME_DEFAULT, /* Get Signature */
	STSAFEA_EXEC_TIME_DEFAULT, /* Generate Signature */
	STSAFEA_EXEC_TIME_DEFAULT, /* Verify Signature */
	STSAFEA_EXEC_TIME_DEFAULT, /* Establish Key */
	STSAFEA_EXEC_TIME_DEFAULT, /* Standby */
	STSAFEA_EXEC_TIME_DEFAULT, /* Verify Password */
	STSAFEA_EXEC_TIME_DEFAULT, /* Encrypt */
	STSAFEA_EXEC_TIME_DEFAULT /* Decrypt */

[nils-cercariolo-st]

Hello,
Indeed it's possible to refine these timings. The timing will always be slightly different per chip (due to security reasons, between +10/-10%) and I'm unfortunately unable to offer a good estimation of these timings right now to you. I will see if we can update the timings for the next release.

What I would recommend though, is to use STSE_USE_RSP_POLLING in stse_conf.h. This allows to use polling at your desired interval (with STSE_MAX_POLLING_RETRY, STSE_FIRST_POLLING_INTERVAL and STSE_POLLING_RETRY_INTERVAL) and would probably be the quickest way to optimize it. You can also measure with a logic analyzer or something similar in polling mode, with very short interval to have an accurate approximation in your specific use case (can depend on command, length of message, the key type etc).

[parmi93]

Thanks, I'll switch to STSE_USE_RSP_POLLING