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Restriction on Use of 8-bit Timers

Dear Customer

With regard to our TLCS-900/L1 Series and TLCS-900/H1 Series of 16-bit microcontrollers, Toshiba have found that the following problem may occur when 8-bit timers are used under certain conditions.

If the timer register of an 8-bit timer is updated under the following conditions, the timer flip-flop may output an unexpected value.

This problem occurs if all the following conditions are met:

  • When the 8-bit timer is used in PWM or PPG mode
  • When the double buffer is enabled
  • When the data in the register buffer is updated immediately before an overflow occurs in the up-counter

This problem can be avoided by software by using either of the following methods:

  1. Disable the double buffer.
    (After reset the double buffer is initially disabled.)
  2. Observe the following timing requirement when writing new data to the register buffer:
    a) In the case of using PWM mode
    Write new data to the register buffer by six cycles before the next overflow occurs, using the interrupt routine to be activated by an overflow interrupt.
    b) In the case of using PPG mode
    Write new data to the register buffer by six cycles before the next cycle compare match occurs, using the interrupt routine to be activated by a cycle compare match interrupt (*).
    (*) An interrupt that specifies when to transfer data from the register bufferto the timer register
Product name
TOSHIBA Microcontrollers TLCS-900/L1 Series
  • TMP91CW12F
  • TMP91PW12F
  • TMP91CW12AF
  • TMP91FY12AF
  • TMP91C815F
  • TMP91C016F
  • TMP91CW18AF
  • TMP91PW18AF
  • TMP91C219F
  • TMP91C820AF
  • TMP91CY22F
  • TMP91FY22F
  • TMP91C824F
  • TMP91C025F
  • TMP91CK27U
  • TMP91CP27U
  • TMP91CP27RUG
  • TMP91CU27U
  • TMP91CU27RUG
  • TMP91FY27U
  • TMP91CW28FG
  • TMP91CY28FG
  • TMP91FY28FG
  • TMP91C829F
  • TMP91C630F

TOSHIBA Microcontrollers TLCS-900/H1 Series
  • TMP92C820FG
  • TMP92CH21FG
  • TMP92CM22FG
  • TMP92CA25FG
  • TMP92CM27FG
  • TMP92CD54IF
  • TMP92FD54AIF
  • TMP94C241CF
  • TMP94C251AF

Note: Discontinued products may not be included in the affected products list. Please contact your local Toshiba office or authorized Toshiba dealer for details.


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·Before creating and producing designs and using, customers must also refer to and comply with the latest versions of all relevant TOSHIBA information and the instructions for the application that Product will be used with or for.