SLAZ225O October   2012  – May 2021 MSP430F47126

 

  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.      PZ100
    3. 5.3 Memory-Mapped Hardware Revision (TLV Structure)
  6. 6Advisory Descriptions
    1. 6.1  CPU19
    2. 6.2  CPU44
    3. 6.3  DMA3
    4. 6.4  DMA4
    5. 6.5  DMA13
    6. 6.6  EEM20
    7. 6.7  FLASH19
    8. 6.8  FLASH24
    9. 6.9  FLASH27
    10. 6.10 FLL3
    11. 6.11 FLL8
    12. 6.12 JTAG23
    13. 6.13 LCDA5
    14. 6.14 LCDA6
    15. 6.15 LCDA7
    16. 6.16 TA12
    17. 6.17 TA16
    18. 6.18 TA21
    19. 6.19 TAB22
    20. 6.20 TB2
    21. 6.21 TB16
    22. 6.22 TB24
    23. 6.23 USCI20
    24. 6.24 USCI21
    25. 6.25 USCI22
    26. 6.26 USCI23
    27. 6.27 USCI24
    28. 6.28 USCI25
    29. 6.29 USCI26
    30. 6.30 USCI28
    31. 6.31 USCI30
    32. 6.32 USCI34
    33. 6.33 USCI35
    34. 6.34 USCI40
    35. 6.35 XOSC5
    36. 6.36 XOSC8
    37. 6.37 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
        }
    }
}