ST10R172L-B0 Datasheet, PDF (1/3 Pages) STMicroelectronics – 16-BIT LOW VOLTAGE ROMLESS MCU

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ST10R172L-B0
16-BIT LOW VOLTAGE ROMLESS MCU
ERRATA SHEET
1 INTRODUCTION
This errata sheet describes the functional problems known in the step B0 of the
ST10R172L-B0. This is the erratasheet of the ST10R172L datasheet version 1.1 of april
2000.
2 FUNCTIONAL PROBLEMS
The following malfunctions are known in this step:
2.1 ST_PWRDN.1: EXECUTION OF PWRDN INSTRUCTION WHILE NMI PIN IS HIGH
When PWRDN instruction is executed while NMI pin is at a high level, power-down mode
should not be entered, and the PWRDN instruction should be ignored. However, under the
conditions described below, the PWRDN instruction may not be ignored, and no further in-
structions are fetched from external memory, i.e. the CPU is in a quasi-idle state. This prob-
lem will only occur in the following situations:
1) the instructions following the PWRDN instruction are located in an external memory, and a multi-
plexed bus configuration with memory tristate waitstate (bit MTTCx= 0) is used,
2) the instruction preceding the PWRDN instruction writes to external memory or an XPeripheral
(XRAM, CAN), and the instructions following the PWRDN instruction are located in external memory. In
this case, the problem will occur for any bus configuration.
Note: the on-chip peripherals still work correctly: if the Watchdog Timer is not disabled, it will
reset the device upon an overflow. Interrupts and PEC transfers, however, can not be proc-
essed. If NMI is asserted low while the device is in this quasi-idle state, power-down mode is
entered.
No problem will occur if the NMI pin is low: the chip will normally enter power-down mode.
Workaround: Ensure that no instruction which writes to external memory or an XPeripheral
precedes the PWRDN instruction, otherwise insert e.g. a NOP instruction in front of PWRDN.
When a multiplexed bus with memory tristate waitstate is used, the PWRDN instruction
should be executed from internal RAM or XRAM.
April 2000
Rev. 1.0
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