topic Re: IIC Levels for S912ZVLA in S12 / MagniV Microcontrollers

IIC Levels for S912ZVLA

Boris_Bloxsberg — Thu, 24 Jul 2025 13:19:24 GMT

Hi,

does some know the input levels for the IIC input of the S912ZVLA.

I didn´t find this in the manual.

Regards

Re: IIC Levels for S912ZVLA

lama — Fri, 25 Jul 2025 07:25:39 GMT

Hi,

The IIC input voltage levels for the S912ZVLA microcontroller are not explicitly listed but they are typically defined by the digital input thresholds for the I/O pins used for SDA and SCL.

Typical IIC Pin Thresholds:

For 5V-tolerant I/O (which is common in the S12Z family), the input high voltage (VIH) is typically

0.65 × VDDx and the input low voltage (VIL) is 0.35 * VDDx.

If VDDx = 5V, then guarenteed value:

VIH>= 3.25V (minimum to be recognized as HIGH)
VIL <= 1.75V (maximum to be recognized as LOW)

Of course, real threshold value is somewhere between (1.75 + 125 mV) and ( 3.25 - 125 mV) considering 250mV hysteresis connected to this threshold for changes between log.0 and log.1

For example

Best regards,

Ladislav

Re: IIC Levels for S912ZVLA

Boris_Bloxsberg — Fri, 25 Jul 2025 08:17:55 GMT

thx

Re: IIC Levels for S912ZVLA

barkerxavierr — Tue, 29 Jul 2025 06:48:20 GMT

Yeah, those VIH/VIL numbers for the S12Z family are pretty standard, especially for 5V-tolerant I/O. Just remember that hysteresis helps a lot with noise, but you really want to Drift Boss make sure your I2C signals are clean and the pull-ups are strong enough, or you’ll chase ghost errors for hours.

Re: IIC Levels for S912ZVLA

lama — Mon, 25 Aug 2025 08:47:25 GMT

Hi,

The only issue I see in the internal pull up. They are really weak 20kohm-50kohm. I suggest to use external ones 1k~10k.

Always use external pull-up resistors (typically 4.7kΩ is a good starting point).

You can leave internal pull-ups disabled, or enable them as a backup — but don’t rely on them for I²C operation.

Best regards,

Ladislav