When the Analogue to Digital Converter converts an analogue value of

(Vrefh-Vrefl)/4 on any ADC channel, there is a risk to get a wrong value. 



When noise occurs on the input, the highest bit of the conversion result

can be erroneously set. 

This is because internal voltage comparators are asynchronous to the ADC

clock.

The error can only occur on the most significant bit when the conversion

result is measured as (Vrefh-Vrefl)/4 exactly.



The error always occurs on a unique value depending on the conversion mode:

- For 12-bit conversion if the result value is 1024 the ADC will

erroneously report a result of 2048. 

- For 10-bit conversion if the result value is 256 the ADC will

erroneously report a result of 512. 

- For 8-bit conversion if the result value is 64 the ADC will

erroneously report a result of 128. 



 

It is not possible to avoid the error occurring, however, it is possible

to minimize or avoid the effects of the error by using one of the

following methods:



- Reject values outside a determined sigma. For instance, when

monitoring slow-moving voltages (i.e. battery level), the software can

discard a conversion result which is greatly different from the previous

result and is the erroneous value.



- Simply discard conversion results of 2048 in 12-bit mode, 512 in

10-bit mode and 128 in 8-bit mode and use the previous result.



- Launch a new conversion when the conversion result is 2048 in 12-bit

mode, 512 in 10-bit mode and 128 in 8-bit mode and use the new result. 

The CPU execution priority encoder evaluates taghits and then 

generates  a breakpoint if a taghit must lead to an immediate 

breakpoint as determined by the DBG module.



If the DBG module indicates that this taghit leads to an immediate 

breakpoint then the CPU loads the execution stage with SWI or BGND thus 

generating the breakpoint.



At simultaneous taghits the lowest channel has priority.

If taghits on 2 channels simultaneously, whereby the lower channel tag 

must be ignored, but the higher channel tag must cause a breakpoint, 

then the breakpoint request is erroneously missed.

Thus if channel[1:0] taghits occur simultaneously whereby channel[0] 

must be ignored but channel[1] must cause a breakpoint, then the 

breakpoint request on channel[1] is erroneously missed and no 

breakpoint generated.



The DBG module recognises the taghit and the state sequencer 

transitions accordingly. Furthermore the taghit causes the DBG module 

to request a  forced breakpoint, which means that a late CPU breakpoint 

occurs. If the tagged instruction is a single cycle instruction, the 

breakpoint occurs at the second instruction following the tagged 

instruction.  

Otherwise the breakpoint occurs at the instruction immediately 

following the tagged instruction.



This bug requires that separate tags are placed on the same 

instruction. This is not a typical case when using exact tag addresses. 

It is more relevant in debugging environments using range modes, where 

tags may cover a whole range. In this case a tagged range may cover a 

tag or another tagged range, making simultaneous taghits possible.



This is a debugging issue only. 

Do not attach multiple tags to the same exact address. 

When attaching multiple tags to the same address by overlapping tag 

ranges in range modes, or covering a tag with a tag range in range 

modes, then the missed tag can be avoided by mapping the final state

change to the lower channel number.



For example the case

Channel[0] tags a range; channel[3] tags an instruction within that 

range. 

From DBG State1 Taghit[0] leads to State2.    (DBGSCR1=$6)

From DBG State2 Taghit[3] leads to FinalState.(DBGSCR2=$5)

In State2 a simultaneous Taghit[3,0] scenario would miss the breakpoint.



This can be avoided by using the alternative DBG configuration

Channel[2] tags a range; channel[0] tags an instruction within that 

range. 

From DBG State1 Taghit[2] leads to State2.    (DBGSCR1=$3)

From DBG State2 Taghit[0] leads to FinalState.(DBGSCR2=$7) 

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.

 

Where the IRQ interrupt is being used in edge-sensitive mode and a 

lower priority interrupt is already pending when an IRQ edge event 

occurs, if the IRQ edge event occurs inside a very narrow (<3ns) window 

just as the pending interrupt vector is being fetched, then a different 

vector other than that relating to either the pending interrupt or IRQ 

will be taken.

 

In the case that a programmed interrupt vector is fetched both the 

originally pending interrupt and the IRQ interrupt request will remain 

pending and will be serviced once the erroneously called service 

routine has completed (and RTI has been executed).



In the case that the incorrect vector fetch is from an unprogrammed 

vector table entry (i.e. erased state = 0xFFFF) then erroneous 

execution from the start of the register space will occur most often 

resulting in an illegal memory access reset, COP reset or Unimplemented 

Instruction Trap occurring. 



In the less likely case that one of the three reset vectors is 

incorrectly fetched then execution will jump to the appropriate reset 

code.  



The following vectors are not affected will not cause erroneous 

behavior if pending: 

$F0 - RTI

$F6 - SWI

$E2 – ECT channel 6

$B2 – CAN0 Rx

$72 – XGATE software trigger 0



This issue is limited to the edge-sensitive mode of the IRQ input only -

 applications not using IRQ interrupts or configured for level-

sensitive IRQ input are not affected.



There is no issue where a pending interrupt has higher priority than 

the IRQ request. 

Where using IRQ in edge-sensitive mode then configure the interrupt 

priority levels of all interrupts being used to ensure that the IRQ 

request always has the lowest priority. 



For new designs, where possible use the IRQ input in level-sensitive 

mode or alternatively use a key-interrupt port. 



There are a number of ‘best practices’ and features of the S12X which 

can help minimize the impact of this errata in the case of it occurring:



1) As ‘best practice’ initialize all unused and unimplemented/reserved 

interrupt vector table locations to point to a dummy interrupt service 

routine (terminated with an RTI). 



2) Where possible, check for appropriate asserted flags in interrupt 

service routines and return / flag a system error if no request flag is 

set.



3) Support is provided on the MCU for managing the following system 

conditions:

* COP watchdog reset 

* Illegal access reset 

* Unimplemented instruction trap

For ‘best practice’ the application's software should be written to 

recover from any of these conditions in a controlled manner. 



4) In the case of erroneous code execution jumping to unused Flash the 

typical practice of filling all unused Flash and RAM space with the op-

code for the SWI instruction will help manage this. SWI exception 

routine should be written in this case to manage this event.

 

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 do

not show the state which is set by PWMLVL bit when the 16-bit counter is

non-zero. 





 

If emergency shutdown mode is required:



In 16-bit concatenation mode, user can disable the related PWM 

channels and set the corresponding general-purpose IO to be the PWM 

LVL value. After a intend period, restart the PWM channels.



 

In low power modes (P-STOP/STOP/WAIT mode) and during PWM7

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

cannot keep the state which is set by PWMLVL bit.  









 

Before entering low power modes, user can disable the related PWM 

channels and set the corresponding general-purpose IO to be the PWM 

LVL value. After a intend period, restart the 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 V02.07 (04

 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.







 

If the PLL is manually turned off (PLLCTL_ PLLON = 0) before a STOP

instruction and the PLL is manually turned on (PLLCTL_PLLON=1) after

execution of the STOP instruction, the PLL might have a premature lock

condition in the case of a STOP instruction being executed with a

pending interrupt and the corresponding interrupt is enabled. In this

case the STOP is executed similar to NOP instruction. 



Due to the manual control of the PLL, the VCO clock is switched on and

off. The PLL lock detection logic uses the VCO clock as well as the

reference clock (based on the external oscillator). The external

oscillator is not stopped because the STOP instruction is executed like

a NOP instruction, which keeps the reference clock running. 



This causes the logic in the PLL lock detection being uncorrelated and

thus resulting in a possible premature LOCK condition (CRGFLG_LOCK=1). 



After the next lock detection cycle the lock is lost (CRGFLG_LOCK=0)

because the VCO clock frequency has not reached the correct value. Some

lock detection cycles later the correct lock condition is reached (VCO

clock frequency reached the correct value) and the LOCK bit is set again

(CRGFLG_LOCK=1). Each transition of the LOCK bit is indicated by the

lock interrupt flag (CRGFLG_LOCKIF). 

Do not modify the PLLON bit around the STOP instruction. 



The clock control and power down/up sequencing is automatically done by

the device CRG module. Only the system clock source selection after exit

from STOP must be controlled by software (CLKSEL_PLLSEL bit) as

described in the Reference Manual. 



Depending on the application if the fast wake-up feature is used the

software also needs to control the bit FSTWKP and bit SCME (both located

in the PLLCTL register) as described in the device Reference Manual when

STOP Mode is entered or exited.





 

Configured for Infrared Receive mode, the SCI may incorrectly set the 

RXEDGIF bit if there are consecutive '00' data bits. There are two 

cases:    



Case 1: due to re-sync of the RXD input, the received edge may be 

delayed by one bus cycle. If an edge (bit = '0') is detected near 

an SCI clock edge, the next edge (bit = '0') may be detected one 

SCI clock later than expected due to re-sync logic. 



Case 2: if external baud is slower than SCI receiver, the next edge 

may be detected later than expected.



This glitch can be detected by the RXEDGIF circuit, but it does not 

impact the final data result because the SCI receive and data recovery 

logic takes samples at RT8, RT9, and RT10.

 



 

Case 1 and case 2 may occurs at same time. To avoid those unexpected 

RXEDGIF at IR mode, the external baud should be kept a little bit 

faster than receiver baud by:

                 P > (1/16)/(SBR)

                        or

                 (P)(SBR)(16)> 1



Where SBR is baud of receiver, P is external baud faster ratio. 

For example:

1.- When SBR = 16, P = 0.4%, this means the external baud should be at 

least 0.4% faster than receiver.

2.- When SBR = 4, P = 1.6%, this means the external baud should be at 

least 1.6% faster than receiver.

 

Case 1 will cover case 2, i.e. case 1 is the worst case. If case1 is 

solved, case 2 is also solved.