OpenDev FanEmu 2

Firmware Version

Applicable firmware versions: 2.0Z

Previous revisions:

• 1.0Z

Device modes

The device can work in two modes:

• Automatic mode (the default) - the measured duty cycle of the CTRL signal determines the effective RPM value, coded by the SENSE signal.
• Manual mode - the SENSE signal is determined by the values, input via the respective commands.

General Frame Format

• Host-to-Device command data must end with a line-feed character (ASCII code 10/0x0A).
• Command data is case-sensitive.
• Device-to-Host reply data is delimited by a line-feed character.
• Empty data frames are permitted and silently ignored.
• All integer parameters are passed as decimal numbers.

Device information

Syntax

Example

Current measured CTRL signal duty

Returns the value with the polarity reversal according to the configuration flags has been already performed.

Syntax

Example

(current duty is 50%)

Current RPM value

Syntax

Example

(SENSE channel currently outputs signal, equivalent to 3000 rpm)

Full RPM value

Returns the maximum RPM value permitted by the current configuration.

Syntax

Example

(Current configuration value is 6800 rpm)

Calculate RPM value for the given duty value

This command computes and outputs the RPM value that would be set if the given value has been measured on the CTRL channel. It does not set or change anything. The computation is performed according the the current curve configuration.

Syntax

Example

Device settings

Note: these are the in-memory settings. They can be changed via the respective commands listed below. In order to make them permanent, issue the 'Write settings' command.

Syntax

The device has 3 configuration parameters:

• flags - a bit field:
  • 0x01 - if set, the CTRL signal polarity is reversed
  • 0x02 - if set, the manual control mode is activated
• full_rpm - the rpm value of the signal that will be output to the SENSE pin when the CTRL signal duty cycle is 100%. Valid range is 0-9000.
• min_duty - (for automatic mode only) - the value of the CTRL signal duty value corresponding to the minimal configured RPM value.

The default values are:

• flags = 0
• full_rpm = 6800
• min_duty = 10

Example

Set configuration flags

Syntax

Example

Get the curve coefficients

Given an input signal duty value, the device computes the RPM value according to the coefficients, stored in the configuration section. Each coefficients entry comprises x,a,b,c,d. The RPM value for duty values inside the (x[i]:x[i+1]) segment are computed according to the formula: S[i](duty) = a[i] + b[i] * (duty - x[i]) + c[i] * (duty - x[i])^2 + d[i] * (duty - x[i])^3

This commands returns the i-th segment contents. The segment number must be a hexadecimal 2-digit value (padded with zero if necessary). If the requested segment is not found, xx is returned.

Syntax

Example

Set the curve coefficients

This command writes coefficients for the i-th segment. The segment number must be a hexadecimal 2-digit value (padded with zero if necessary) and less than 27.

Syntax

Example

Apply coefficients

After changing the coefficients, either this command, or a device reset must be issued.

Syntax

Set the RPM value

Manual mode only

Valid values are 0..9000

Syntax

Example

Set the RPM percentage

Manual mode only

The previous command sets the immediate value. This command sets the rpm as a percent of the configured full rpm value. Valid values are 0..100

Syntax

Example

Device voltage and temperature

The temperature value is in degrees centigrade, the voltage is in millivolts. Note: these are the temperature and the voltage of the MCU core. They do not reflect the ambient temperature and the fan input voltage respectively.

Syntax

Example

Device reboot

Syntax

Firmware update

Puts the device in the DFU bootloader mode.

Syntax