When the foreground receive buffer (RxFG) is read with the Receiver Full

Flag (RXF) set, the value of one or more data bytes may be incorrect due

to corruption after the message reception. The corruption can occur at

the end of a message transmission from any of the three transmit message

buffers of the same msCAN module. The affected data byte is overwritten

by a byte of the corrupting transmit buffer's Time Stamp Register, TSRH

for even, TSRL for odd addresses affected, respectively. The value

written is zero ($00) if the internal timer has not been enabled (TIME=0

in CANCTL0).



The corruption can only occur if all of the following three conditions

are met:



1. Rx and Tx message length relationship

If the number of data bytes transmitted, n, is five or less, Data

Segment Register (n+2) in RxFG is corrupted, i.e. DSR2 if n=0, .., DSR7

if n=5.

No corruption occurs for n > 5. Also, DSR0 and DSR1 are never affected.



2. Timing

A received message may contain corrupted data if RxFG is read after the

end of a message transmission from the same msCAN module.

No corruption is seen if all received messages are read within the time

window beginning when RXF is set and ending with the completion of

transmission of a subsequent message by the same msCAN module (the

'green window'). The width of the green window depends on many factors:

application software (Tx message scheduling, Rx/Tx interrupt priorities,

etc.), bus load, baud rate, and transmit message length. The minimum

(guaranteed) green window width is 376us for 125kbps, for example. This

minimum value occurs only in case of a transmit message following

back-to-back to the receive message, and for zero data bytes and zero

stuff bits. The green window width inversely scales with the baud rate.



3. Receive FIFO Buffer #

Only receive buffer 0 (Rx0) of the 5-stage FIFO can be affected.

At least four out of every five messages received are not affected. 

In affected systems where the lengths of messages can be adjusted, using

six or more bytes for transmission eliminates the issue completely.

Systems using an MCU with unused msCAN modules should use one to

transmit only and one to receive only, to completely avoid the issue.

For other systems the likelihood of problem occurrence can be further

reduced by maximizing the receive interrupt priority, i.e. use CAN0 for

the most critical bus in a multi-bus application, and/or promoting the

msCAN receive interrupt to highest priority using the HPRIO register.

In (control) systems where the signal representation can be adjusted,

and the time stamp is not used (TIME=0), mapping $00 to an 'illegal'

signal would allow problem detection and appropriate software means of

reaction.

In systems where all byte values are legal (e.g. data download),

checksums and/or parities can be used to signal problem occurrence and

allow for proper handling (e.g. request for retransmission).

Alternatively, the use of data filter algorithms may suppress or at

least reduce the effect of the problem. 

When the foreground receive buffer (RxFG) is read, with the Receiver

Full Flag (RXF) set, the value of the Time Stamp Register may be

incorrect due to corruption. The Time Stamp Register is written

correctly when the message is received, but may be overwritten by the

timer value at the end of a subsequent reception. The corruption can

only occur close to a data overrun, when the receive buffer FIFO is

full.



The problem occurs whenever the following two conditions are met: 



1. Receive buffer system is full 

All five receive buffers contain valid messages waiting to be read by

the application. 



2. Another valid message is seen on the bus. This message must be sent

from another node, i.e. it must not be transmitted from the respective

msCAN module itself. 



At the end of the message in 2. the Time Stamp Register of the oldest

message in the receive FIFO is overwritten. 



Note: if the message in 2. passes the message filter system the Overrun

Interrupt Flag (OVRIF) is also set. 

The application software has to ensure to read the receive messages in

due time to avoid data overrun in any case. This will automatically

minimize the risk of a Time Stamp Register overwrite event. 

If a particular error condition occurs within the end of frame segment

(EOF) of a CAN message, the msCAN module recognises and accepts a

non-valid message as being valid, contrary to the CAN specification. The

msCAN module incorrectly validates messages after five recessive bits of

the end of frame instead of after six bits. If a bus error occurs during

the sixth bit of end of frame, the msCAN module will already have

accepted the message as valid, even although an error frame is

transmitted and the receive error counter is incremented.



The CAN protocol states that message validation differs between bus

transmitter and receiver devices (refer to part B, section 5 of CAN

protocol for details). In the case where the 7th bit of the EOF segment

is dominant, the message is valid for the receiver but not for the

transmitter. This erratum extends this case to the 6th bit of the EOF

segment. 

This erratum will not be an issue if the application software is

protected against the known double receive problem of the CAN protocol.

This problem occurs when a message is not recognised as valid by the

transmitter, but is recognised as valid by a receiver, as described

above. When this happens, the message is re-transmitted and hence the

receiver will receive the same message twice.

 

The flash program temperature range specification has been reduced. The

specification now stipulates that flash program operations must take

place between temperatures of 0C and 125C ambient.



In addition, the flash program times have been increased as follows:



                                                   Programming Time 

                                                    Min.      Max.

Single Word Program                      (Tswpgm)    66.0us    99.2us  

Flash Row Program - Consecutive Word     (Tbwpgm)    40.4us    57.8us

Flash Row Program - 64 words             (Tbrpgm)  2608.7us  3742.7us



Actual programming time will vary between the above bounds depending on

flash clock and bus clock frequencies.



Important Notes: 

1) Program time is internally controlled by the flash state machine. 

   No action needs to be taken by users in connection with this erratum. 

2) Both flash erase and flash read temperature specifications and 

   operation times are unaffected by this erratum.

3) EEPROM is unaffected by this erratum.  

None.

Upon leaving BDM active mode, the CPU return address is stored

temporarily for a few cycles in the BDM shift register. If a BDM command

transmission is detected during this time, the return address will be

manipulated in the BDM shift register. This situation is likely to occur

when a CPU BGND instruction is executed in user code during debugging

under the following conditions:



(i) The BDM module is not enabled AND

(ii) BDM commands are sent from the host



If this situation occurs, the CPU will execute BDM firmware and will

check the status of the ENBDM bit in the BDMSTS register. If the BDM is

disabled, the ENBDM bit will be clear, and hence the BDM firmware will

be exited and the shift register manipulation described above will occur. 

Avoid using the BGND instruction when the ENBDM bit in the BDMSTS

register is cleared. 

At oscillator frequencies above 4MHz the Program step of the EEPROM

Sector-Modify command can fail depending on the bus frequency. As a

result, no programming of the EEPROM occurs. There is no impact to the

Erase step of the Sector-Modify command. Since a partial programming of

the word cannot occur, there is not a reliability issue caused by the

Sector-Modify command if the programmed word is verified.

 

   Oscillator             Bus

   Frequency           Frequency

   ----------    ----------------------

     4MHz             No Issue

     8MHz        Fbus <20MHz : No issue

    16MHz        Fbus <16MHz : No issue





 

Use seperate Erase and Program commands in place of the Sector-Modify

command. If the Sector-Modify command is used and fails the program step

as confirmed by a user verification step, a Program command alone can be

used to effectively complete the operation since the erase step does

successfully erase the sector. 

If the ECLK is used as an external bus control signal (ESTR=1) the first

external access is lost after switching from a single chip mode with

enabled ECLK output to an expanded mode. The ECLK is erroneously held in

the high phase thus the first external bus access does not generate a

rising ECLK edge for the external logic to latch the address. The ECLK

stretches low after the lost access resulting in all following external

accesses to be valid. 

Enter expanded mode with ECLK output disabled (NECLK=1). Enable the ECLK

after switching the mode before executing the first external access. 

When an OC7M bit is set, an erroneous normal output compare event can 

happen on a timer port if the compare action is selected as "Timer 

disconnected from output pin logic ".

 

Corresponding configuration:

*  TIOSx = 1 --> Output compare mode

*  OMx = OLx = 0 --> Output compare logic disconnected from the pin

*  OC7Mx = 1 --> Mask bit set for OC7 event











 

Set OC7Mx = 1 only for channels where the output compare action should 

drive the pin, and OC7Mx = 0 for all other channels where the pin is 

required to be disconnected from the output compare logic. 

With the SPI configured as a slave, clearing the SPE bit (to disable 

the SPI) together with clearing the CPHA bit while the SS pin is low 

causes the transmit shift register to be locked for the next 

transmission following the SPI being re-enabled as a slave with SS 

still being low. 



This means new transmit data is not accepted for the first 

transmission after re-enabling the SPI (indicated by SPTEF staying low 

after storing transmit data into SPIDR), but for the next following 

transmission.



 

When disabling the slave SPI, CPHA should not be cleared at the same time. 

Starting a conversion with a write to ATDxCTL5 or on an external trigger

event, and aborting immediately afterwards with a write to ATDxCTL0,

ATDCTL1, ATDxCTL2 or ATDxCTL3 can fail to stop the conversion process. 

Only write to ATDxCTL4 to abort an ongoing conversion sequence.



Use the recommended start and abort procedures from the Block Guide.

Section : Initialization/Application Information 

Subsection: Setting up and starting an A/D conversion 

Subsection: Aborting an A/D conversion 

The initial eight ID bits will be corrupted if a message is set up for

transmission during the third bit of INTERMISSION and a dominant bit is

sampled leading to an early-SOF*.



The CRC is calculated from the resulting bit stream so that the

receiving nodes will still validate the message.



An early-SOF condition may only occur if the oscillators in the network

operate at a tolerance range which could lead to a cumulated phase error

after 11 bit times larger than phase segment 2. 



In case arbitration is lost during transmission of the corrupt

identifier, a non-corrupted ID will be sent with the next attempt if the

transmit request remains active.



*The CAN protocol condition referred to as 'early-SOF' in this erratum

is detailed in "Bosch CAN Specification Version 2.0" Part A, section 9,

and a Note to section 3.2.5 INTERFRAME SPACING – INTERMISSION in Part B. 

Due to increased oscillator tolerance a transmission start in the third

bit of intermission is possible and allowed. The errata can be avoided

when calculating the maximum oscillator tolerance of the overall CAN

system. The phase error after 11 bit times due to the oscillator

tolerance should be smaller than phase segment 2.



If an early-SOF cannot be avoided the following methods will provide

prevention:



- Assigning the same value to all upper eight ID bits in the network

- Allocating dedicated data length codes (DLC) to every identifier used 

  in the network and checking for correspondence after reception

- Assigning only IDs (x) which do not consist of a combination of other 

  assigned IDs (y,z) and using the acceptance filters to reject 

  erroneous messages, i.e. 

  - for standard frames: IDx[11:0]  != {IDy[11:3], IDz[2:0]}

  - for extended frames: IDx[28:21] != {IDy[28:21],IDz[20:0]} 

It is possible that after the device enters Stop or Pseudo-Stop mode it

may reset rather than wake up normally upon reception of the wake-up

signal. 



CONDITIONS: This event will only happen provided ALL of the following

conditions are met: 

    1) Device is powered by the on-chip voltage regulator. 

    2) Device enters stop or pseudo-stop mode by execution of STOP

instruction by the CPU (provided the S-bit in CCR is cleared) 

NOTE: The part enters stop mode either after 12 oscillator clock cycles

with the PLL disengaged or 3 PLL clock cycles and 8 oscillator clock

cycles with the PLL engaged after the STOP command is executed. 

    3) The wake-up signal is activated within a specific very short

window (typically 11ns long, not longer than 20ns). The position of the

window varies between different devices, however it never starts sooner

than 1.6µs and never ends later than 4.7µs after the stop mode entry. 



This really narrow width of the susceptible window (20ns maximum) makes

the erratum unlikely to ever show in the applications life. 



The incorrect behavior will never occur if ANY of the wake-up conditions

are met at the time when the stop mode entry is attempted (an enabled

interrupt is pending). 



EFFECT: 

If this incorrect behavior occurs, the device will Reset and indicate a

Low Voltage Reset (LVR) as the reset source. 

The device will operate normally after the reset.  

None. 



-- 



Asynchronous Low Voltage Resets are possible in any microcontroller

application (due to power supply drops) and the integrated LVR and LVI

features and dedicated LVR reset vector are provided to manage this fact

cleanly. For best practice, the application's software should be written

to recover from a Low Voltage Reset in a controlled manner. An

application software written to deal with valid Low Voltage Resets

should correctly manage erroneous LVR events. 



It can also be possible to avoid erroneous Low Voltage Resets from

synchronous wake-up events by configuring the application software to

ensure that the entry into stop occurs at such a time, in relation to

the wake-up event timer, that a wake-up event does not occur within

1.6µs to 4.7µs after Stop/Pseudo-Stop entry.  

When the ATD is started with write to ATDCTL5

and, which is very unusual and not necessary,

within a certain period again started with write

to ATDCTL5. The conversion will not start at all.

This does only happen if the two consecutive writes to ATDCTL5 occur 

within one "ATD clock period". An ATD clock period is defined by a full 

rollover of the ATD clock prescaler. That is for example PRS[4:0] = 2 -

> (2+1)*2 = within 6 bus cycles.

 

Only write once to ATDCTL5 when starting a conversion.



Use the recommended start and abort procedures from the Block Guide.

Section : Initialization/Application Information Subsection: Setting up

and starting an A/D conversion Subsection: Aborting an A/D conversion 

If the PWM emergency shutdown feature is enabled (PWM7ENA=1) and PWM

channel 7 is disabled (PWME7=0) another lower priority function

available on the related pin can take control over the data direction.

This does not lead to a problem if input mode is maintained. If the

alternative function switches to output mode the shutdown function may

unintentionally be triggered by the output data.

 

When using the PWM emergency shutdown feature the GPIO function on the

pin associated with PWM channel 7 should be selected as an input. 



In the case that this pin is selected as an output or where an

alternative function is enabled which could drive it as an output,

enable PWM channel 7 by setting the PWME7 bit. This prevents an

active shutdown level driven on the (output) pin from resulting in an

emergency shutdown of the enabled PWM channels.

 

The pulse width of an output compare (which resets the free running

counter when TCRE = 1) will measure one more bus clock cycle than 

expected. 



 

The specification has been updated. Please refer to revision 01.05 (05 

May 2010) or later.



In description of bitfield TCRE in register TSCR2,a note has been added:

TCRE=1 and TC7!=0, the TCNT cycle period will be TC7 x "prescaler

counter width" + "1 Bus Clock". When TCRE is set and TC7 is not equal to

0, then TCNT will cycle from 0 to TC7. When TCNT reaches TC7 value, it

will last only one bus cycle then reset to 0.









 

When the PWM is used in 16-bit (concatenation) channel and the emergency

shutdown feature is being used, after de-asserting PWM channel 7

(note:PWMRSTRT should be set) the PWM channels (PP0-PP6) do not show the

state which is set by PWMLVL bit when the 16-bit counter is non-zero. 

 

None. 

In low power modes (stop/p-stop/wait – PSWAI=1) and during PWM PP7

de-assert and when PWM counter reaching 0, the PWM channel outputs

(PP0-PP6) cannot keep the state which is set by PWMLVL bit.  



 

None.