NUCLEO_F401RE I2C broken

[c1728p9]

Description

• Type: Bug
• Priority: Major

I2C failures with EEPROM (I2C)

I2C - EEProm Read (fails with ARMCC, GCC)
I2C - TMP102 Temperature Read (fails with GCC, works with ARMCC)

Target
NUCLEO_F401RE

Toolchain:
GCC_ARM

meed-os sha:
22ec73b Merge pull request #2948 from jamike/Fixed_iarm_debug_built_failed

Steps to reproduce
Tests available here https://github.com/armmbed/ci-test-shield
Hardware components here https://github.com/ARMmbed/mbed-HDK/tree/master/Production%20Design%20Projects/CITestShield

CC: @adustm @bcostm @screamerbg

[c1728p9]

The commit 8982ff1 (#2622) appears to have introduced this problem. At the end of a read a nack is no longer sent which causes the IIC device to keep holding SDA low.

Logic capture on 22ec73b when running test:

Logic capture on same commit but with 8982ff1 reverted:

CC: @egostm

[c1728p9]

This is likely the cause of the I@C failures in #2956 and #2959.

[betzw]

Should already be fixed by PR #2972

[screamerbg]

As @betzw pointed, no longer an issue after PR #2972 @c1728p9. Close if you can confirm

[c1728p9]

Tested #2972 and it passes the I2C tests. Logic capture also looks correct.