Peripherals partly supported by the emulators

AN2695

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Peripherals partly supported by the emulators

Some of the ST10F276Z5 peripherals are partly supported by the emulators. This section

describes the limitations encountered in emulating these peripherals.

2.1

A/D converter

Compared to that of the ST10F269Zx, the ST10F276Z5 ADC has been improved to support

24 channels instead of 16 and to have a faster conversion time. These improvements have a

small impact on the emulation and compatibility with the ST10F269Zx. They are explained

in the following sections.

2.1.1

ADC calibration process

Description: the ST10F276Z5 ADC auto-calibration process cannot be interrupted for

conversion. It was interruptible with the ST10F269Zx and the ST10 bond-out. The duration

of the calibration of the ST10F276Z5 is 40 650 cycles, which is very close to the 40 000

CPU clock cycles of the ST10F269Zx. The calibration starts automatically on each Reset

(external_hardware, internal_hardware or software reset). During the auto-calibration, the

ADCON.ADBSY bit is set (same behavior as the ST10F269Zx and ST10 bond-out).

check the busy bit in the ADCON register (ADBSY=1 during auto-calibration). There is no

impact for subsequent ADC configuration changes.

Hardware impact: no impact.

ST10F276Z5 emulation impact: no impact if ST’s advice is implemented. Real-time

differences due to the change in calibration process duration have to be analyzed for each

application.

2.1.2

ADC conversion timings

Description: to allow faster conversion, the ADC sampling clock has been changed. For the

same software configuration, this results in different sampling times for the ST10F276Z5

compared to the ST10F269Zx and the ST10-emulator. To keep the same real-time behavior,

the ADC overall timings between 2 consecutive conversions have not been changed.

Software impact: to avoid issues caused by sampling time not coherent with external RC

filters, it is proposed to modify the software to check which processor of the ST10F276Z5 or

the emulator is running the software (by checking ID-chip register), and to set the ADCON

sampling clock accordingly.

Hardware impact: no impact.

ST10F276Z5 emulation impact: no impact if ST’s advice is implemented.