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I'd like to program a LIS331EB which is an ST product with an integrated cortex-M0 core. ST says it can be programmed with ST-link even though it is neither an STM32 nor STM8. The lis331eb's core and SWDIO- SWCLK pins run from 1.8V.

When I'd like to program my device I can see on the oscilloscope that the SWDIO and SWCLK io levels are 3V, only the reset line got the core's 1.8V IO level.

Do you think it is OK? I did not find anywhere that the SWDIO/SWCLK pins would be 3V tolerant, so it seems like a problem to me...

(I use ST-link/V2 which should be able to program down to 1.65V target voltage.)

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The ST-LINK/V2 has a dedicated pin TVCC (target VCC) to detect the voltage of the application board and to ensure that the right voltages are used.

Usually the detected voltage is reported by the utility used for programming and can be inspected before the programming is initiated.

So it should be safe to connect this pin and try to see if the target voltage is detected correctly.

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  • \$\begingroup\$ This is probably a difference between a "real" ST-LINK and the on-board functionality of evaluation boards or simple single-chip dongles built around an STM32F103 - while those can program many targets, they don't have adaptive voltage circuitry. \$\endgroup\$ – Chris Stratton Jun 26 '17 at 18:35

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