[149] TWIM: First clock pulse after clock stretching may be too long or too short

This anomaly applies to IC Rev. Rev 2, build codes QFAA-E00, CIAA-E00, QFAB-E00.

It was inherited from the previous IC revision Rev 1.

Symptoms

When the TWI slave exits a clock stretching state, the first clock pulse from the master is too long or too short.

The following deviations from the normal clock pulse length can occur:
400 kHz
  • Minimum: 0.7 µs
  • Maximum: 3.0 µs
100 kHz
  • Minimum: 0.7 µs
  • Maximum: 11.0 µs

Conditions

TWI slave uses clock stretching.

Consequences

The slave may give an error condition due to a too long or too short clock pulse or the pulse may be lost. This depends on the slave clock stretching behavior.

Workaround

None.