SLAZ372Q October   2012  – May 2021 MSP430FG479

 

  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.      PN80
      3.      ZCA113
    3. 5.3 Memory-Mapped Hardware Revision (TLV Structure)
  6. 6Advisory Descriptions
    1. 6.1  CPU4
    2. 6.2  CPU19
    3. 6.3  EEM20
    4. 6.4  FLASH19
    5. 6.5  FLASH24
    6. 6.6  FLASH27
    7. 6.7  FLL3
    8. 6.8  FLL6
    9. 6.9  JTAG23
    10. 6.10 LCDA5
    11. 6.11 LCDA7
    12. 6.12 SDA6
    13. 6.13 TA12
    14. 6.14 TA16
    15. 6.15 TA21
    16. 6.16 TAB22
    17. 6.17 TB2
    18. 6.18 TB16
    19. 6.19 TB24
    20. 6.20 USCI20
    21. 6.21 USCI22
    22. 6.22 USCI23
    23. 6.23 USCI24
    24. 6.24 USCI25
    25. 6.25 USCI26
    26. 6.26 USCI28
    27. 6.27 USCI30
    28. 6.28 USCI34
    29. 6.29 USCI35
    30. 6.30 USCI40
    31. 6.31 XOSC5
    32. 6.32 XOSC8
    33. 6.33 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
        }
    }
}