Texas Instruments Errata MSP430FG6426, Manual

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UCS11
(continued)
UCS Module
changing the SELM/SELS/SELA bits in the UCSCTL4 register to prevent unintended NMI.
Alternatively it can be handled accordingly (clear falsely set fault flags) in the Interrupt
Service Routine to ensure proper OFIFG clearing.
USCI26 USCI Module
Category Functional
Function Tbuf parameter violation in I2C multi-master mode
Description In multi-master I2C systems the timing parameter Tbuf (bus free time between a stop
condition and the following start) is not guaranteed to match the I2C specification of 4.7us
in standard mode and 1.3us in fast mode. If the UCTXSTT bit is set during a running I2C
transaction, the USCI module waits and issues the start condition on bus release causing
the violation to occur.
Note: It is recommended to check if UCBBUSY bit is cleared before setting UCTXSTT=1.
Workaround None
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)
{
www.ti.com Advisory Descriptions
SLAZ669P – MAY 2015 – REVISED AUGUST 2021
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