SLAZ221P October   2012  – May 2021 MSP430F4618

 

  1. 1Functional Advisories
  2. 2Preprogrammed Software Advisories
  3. 3Debug Only Advisories
  4. 4Fixed by Compiler Advisories
  5. 5Nomenclature, Package Symbolization, and Revision Identification
    1. 5.1 Device Nomenclature
    2. 5.2 Package Markings
      1.      ZQW113
      2.      PZ100
    3. 5.3 Memory-Mapped Hardware Revision (TLV Structure)
  6. 6Advisory Descriptions
    1. 6.1  ADC18
    2. 6.2  ADC25
    3. 6.3  CPU8
    4. 6.4  CPU16
    5. 6.5  CPU19
    6. 6.6  DMA3
    7. 6.7  DMA4
    8. 6.8  FLL3
    9. 6.9  FLL6
    10. 6.10 LCDA5
    11. 6.11 LCDA7
    12. 6.12 RTC1
    13. 6.13 TA12
    14. 6.14 TA16
    15. 6.15 TA18
    16. 6.16 TA21
    17. 6.17 TAB22
    18. 6.18 TB2
    19. 6.19 TB16
    20. 6.20 TB18
    21. 6.21 TB24
    22. 6.22 USCI16
    23. 6.23 USCI19
    24. 6.24 USCI20
    25. 6.25 USCI21
    26. 6.26 USCI22
    27. 6.27 USCI23
    28. 6.28 USCI24
    29. 6.29 USCI25
    30. 6.30 USCI26
    31. 6.31 USCI27
    32. 6.32 USCI30
    33. 6.33 USCI34
    34. 6.34 USCI35
    35. 6.35 USCI40
    36. 6.36 WDG2
    37. 6.37 XOSC5
    38. 6.38 XOSC8
    39. 6.39 XOSC9
  7. 7Revision History

USCI34

USCI Module

Category

Functional

Function

I2C multi-master transmit may lose first few bytes.

Description

In an I2C multi-master system (UCMM =1), under the following conditions:

(1)the master is configured as a transmitter (UCTR =1)

AND

(2)the start bit is set (UCTXSTT =1);

if the I2C bus is unavailable, then the USCI module enters an idle state where it waits and checks for bus release. While in the idle state it is possible that the USCI master updates its TXIFG based on clock line activity due to other master/slave communication on the bus. The data byte(s) loaded in TXBUF while in idle state are lost and transmit pointers initialized by the user in the transmit ISR are updated incorrectly.

Workaround

Verify that the START condition has been sent (UCTXSTT =0) before loading TXBUF with data.

Example:
#pragma vector = USCIAB0TX_VECTOR
__interrupt void USCIAB0TX_ISR(void)
{
// Workaround for USCI34
    if(UCB0CTL1&UCTXSTT)
    {
                                                                       // TXData = pointer to the transmit buffer start
                                                                       // PTxData = pointer to transmit in the ISR
        PTxData = TXData;                                   // restore the transmit buffer pointer if the Start bit is set
    }
//
    if(IFG2&UCB0TXIFG)
    {
        if (PTxData < = PTxDataEnd)                      // Check TX byte counter
        {
            UCB0TXBUF = *PTxData++;                 // Load TX buffer
        }
        else
        {
            UCB0CTL1 |= UCTXSTP;                        // I2C stop condition
            IFG2 &= ~UCB0TXIFG;                          // Clear USCI_B0 TX int flag
            __bic_SR_register_on_exit(CPUOFF);      // Exit LPM0
        }
    }
}