DAP_TI_Info

Get information about Test Input channel parameters of the CMSIS-DAP Debug Unit. More...

Get information about Test Input channel parameters of the CMSIS-DAP Debug Unit.

The DAP_TI_Info Command provides information about additional Test Inputs that are possible to capture with the CMSIS-DAP Debug Unit.

DAP_TI_Info Request:

| BYTE | BYTE | BYTE ***|
> 0x1D | ID   | Channel |
|******|******|*********|

• ID: Request Identifier to obtain information in the Response:
  • 0x00 = Get general Test Input channel parameters (Channel value not used).
  • 0x01 = Get parameters of a specific Test Input Channel.
  • 0x02 = Get possible data capturing frequencies.
• Channel: channel number.

DAP_TI_Info Response for ID=0x00: Get general Test Input channel parameters

| BYTE | BYTE ****|
< 0x1D | Channels |
|******|**********|

• Channels: number of channels available in the Debug Unit.

DAP_TI_Info Response for ID=0x01: Get parameters of a specific Channel

| BYTE | BYTE ***| BYTE ******| BYTE ***| LWORD ***| LWORD *****| BYTE ****| FLOAT *| FLOAT *|
< 0x1D | Channel | Attributes | NumBits | IdString | UnitString | Compress | MinVal | MaxVal |
|******|*********|************|*********|**********|************|**********|++++++++|++++++++|

• Channel: channel number that information belongs to.
• Attributes: attributes of the data channel
  • Bit 0..1: DataSize: number of bytes recorded (0=BYTE, 1=SHORT, 2=WORD)
  • Bit 2..3: NumRanges: channel data provides additional range bits (see below)
  • Bit 4: DT_TimeStamp: 1= channel provides time stamp based on Test Domain Timer
• NumBits: resolution of the channel in bits
• IdString: is a up to 8 character 8-bit US ASCII string that identifies the channel
• UnitString: is a up to 8 character 8-bit US ASCII string that identifies the measurement unit of the channel (V, mA, kHz)
• Compress: describes the difference communication that is optionally available (see below)
• MinVal: minimum data value (= 0) represents the MinVal. Repeated for each range.
• MaxVal: maximum data value result represents the MaxVal. Repeated for each range.

Note

NoRanges: specifies if the channel data has data ranges; possible values are:

• 0 = 1 range (1 MinVal/MaxVal value pair in the response).
• 1 = 2 ranges (2 MinVal/MaxVal value pairs are provided in the response)
• 2 = 4 ranges (4 MinVal/MaxVal value pairs are provided in the response)

Compress specifies a method for data differences by this channel.

• 0 = no data differences can be communicated. Only Contiguous Value Format is transmitted in DAP_TI_TransferBlock Response.
• 1 = data differences are transmitted when a single bit is different.
• 2 = new data are transmitted when a value has a significant difference. The least significant 3-bits are ignored. This is useful for A/D values.
• 3 = new data are transmitted when a value has a significant dynamic difference. Only the uppermost 8-bits are considered. This is useful for dynamic A/D values such as the currency consumption of a device.

Data Value Scaling: the information NoBits, MinVal, MaxVal is used to convert the binary data value into a floating data value for displaying purposes. If both MinVal and MinMax are 0 no scaling formula is provided and raw data may be displayed instead. Scaling considers the NoBits value, for example at 12-bit resolution the maximum data value is 0x3FF.

Data Ranges: the information NoRanges, NoBits allows scaled data value based on range information. The range information is provided in the upper data bits. For example a data channel with NoBits=12 and NRanges=2 provides in bit 0..11 the data value and in bit 12..13 the range value.

Example 1: parameters for a channel that supports voltage measurement

IdString = 'U0'            // Voltage symbol for U0 input
UnitString = 'V';          // ASCII character to denote voltage
NoBits = 10;               // 10 bit A/D resolution
NoRanges = 0;              // no ranges are supported
Compress = 2;              // data differences may be communicated
MinVal = 2.5;              // A/D result = 0x000 represents 2.5V
MaxVal = 6.0;              // A/D result = 0x3FF represents 6.0V

Example 2: parameters for a channel that supports current measurement with two ranges

IdString = 'I';            // Current symbol for I input
UnitString = 'mA';         // ASCII character to denote milli Ampere
NoBits = 12;               // 12 bit A/D resolution (bit 0 .. 11 of data values contain A/D result)
NoRanges = 1;              // 2 ranges are supported (bit 12 of data values contains range)
Compress = 3;              // dynamic data differences may be communicated
MinVal[0] = 0;             // A/D result = 0x000 in range 0 represents 0.0mA
MaxVal[0] = 1.0;           // A/D result = 0xFFF in range 0 represents 1.0mA
MinVal[1] = 4.0;           // A/D result = 0x000 in range 0 represents 4.0mA
MaxVal[1] = 20.0;          // A/D result = 0xFFF in range 0 represents 20.0mA

For a channel that reports MinVal = MaxVal = 0 the formula needs to be provided by the debugger as the debug unit is using perhaps an external shunt resistor.

DAP_TI_Info Response for ID=0x02: Get possible data capturing frequencies for recording of a specific channel

| BYTE | BYTE ***| BYTE ********|DWORD ++++|
< 0x1D | Channel | NoSelections |Frequency |
|******|*********|**************|++++++++++| 

• Channel: channel number that information belongs to.
  • Channel = 0..0xF: information of the selected channel
  • Channel = 0xFF: information for common channel data capturing
• NoSelections: number of possible capture frequencies
  • NoSelections = 0: channel does not support data recording
  • NoSelections = 1..15: channel allows selection of individual data capture frequencies.
  • NoSelections = 0xFF: channel allows selection of a common data capture frequency.
• Frequency: capture frequencies (repeated as indicated by NoSelection = 1..15)
  • Frequency[0] capture frequency for CapSelect=0 (see DAP_TI_Capture)
  • Frequency[1] capture frequency for CapSelect=1 (see DAP_TI_Capture)
  • Frequency[n] capture frequency for CapSelect=n (see DAP_TI_Capture)