4. Defining Registers

The registers block is the core of your specification. It maps the memory addresses to the fields we defined earlier.

Example 1: A Read-Only Data Register (TEMP)

The Temperature register (Address 0x00) contains the sensor data.

Datasheet Page 21:

Table 7-5. TMP1075 Register Map

ADDRESS	TYPE	RESET	ACRONYM	REGISTER NAME
00h	R	0000h	TEMP	Temperature result register

Table 7-7. Temperature Register Field Description

BIT	FIELD	TYPE	RESET	DESCRIPTION
15:4	T[11:0]	R	000h	12-bit, read-only register that stores the most recent temperature conversion results.

registers:
  - address: 0x00
    name: Temperature
    symbol: TEMP
    reset: 0x0000
    fields:
      - name: Temperature
        symbol: T
        bits: [ 15, 4 ]
        access: [ r ]
        description: "12-bit, read-only register..."
        format:
          representation: tc
          unit: "Celsius"

Overriding Defaults

Notice we included access: [ r ]. This overrides the global default of [ r, w ] because this specific register is Read-Only.

Understanding format

• representation: tc: Tells the generator this is a Two's Complement signed integer.
• unit: "Celsius": Purely for documentation, letting the user know what the value represents.

Key Concepts from this Example:

• address, name, symbol, and reset are copied directly from the register map table.
• fields: Contains a list of all bit-fields within this register.
• bits: [ 15, 4 ]: The [high, low] bit range for this field.
• access: [ r ]: This field is Read-Only, so we override the register's default [r, w] access.
• format:: The format section specifies the representation, which is two's-complement or tc. It also specifies the unit which is a text representation of the units that the field corresponds to.

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Example 2: A Complex Configuration Register (CFGR)

The Configuration register (Address 0x01) mixes basic bits with Enums.

Datasheet Reference (Page 22):

Table 7-5. TMP1075 Register Map

ADDRESS	TYPE	RESET	ACRONYM	REGISTER NAME
01h	R/W	60A0h	CFGR	Configuration register

Table 7-8. Configuration Register Field Description

BIT	FIELD	TYPE	RESET	DESCRIPTION
14:13	R[1:0]	R (TMP1075N)	11	Conversion rate setting when device is in continuous conversion mode
10	POL	R/W	0	Polarity of the output pin

registers:
# ... other registers ...
- address: 0x01
  name: Configuration
  symbol: CFGR
  reset: 0x60A0
  fields:
    # ... other fields ...
    - name: Conversion Rate
      symbol: R
      bits: [ 14, 13 ]
      access: [ r ] # This field is Read-Only on TMP1075N
      description: "Conversion rate setting when device is in continuous conversion mode"
      enum: R # Links to the global 'R' enum
      reset: Conversion Rate 250 # Maps to the 'name' in the 'R' enum

    # ... other fields ...
    
    - name: Alert Polarity
      symbol: POL
      bits: [ 10, 10 ]
      # access: is set to the default [ r, w ]
      description: "Polarity of the output pin"
      enum: POL # Links to the global 'POL' enum
      reset: Low # Maps to the 'name' in the 'POL' enum
    # ... other fields ...

Linking Enums

• enum: R: This links the field to the global R enum we defined in Step 3. The generated code will force you to use a valid R enum value when writing to this field.
• access: [ r ]: The CFGR register is R/W, but the R (Conversion Rate) field is Read-Only on the TMP1075N variant. This access key overrides the parent register's access setting.
• reset: Conversion Rate 250: The datasheet states the reset for R[1:0] is 11, which corresponds to the "250 ms conversion rate" enum. By using the name from the enum, we make the reset value self-documenting. The generator will resolve this string to 0b11 or the programming language equivalent.
• enums and registers: The enums and registers are in two separate sections, and are linked together using the enum name as mentioned above. All names are Title Case.
• reset: 0x60A0: For each field, reset: <Name> is defined to set the field specific reset value. This is useful for generators that need to initialize and reset fields individually, while the register-level reset: 0x60A0 documents the full reset value from the datasheet for register level operations.

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Summary

You have now defined:

1. Metadata: The chip identity.
2. Enums: Reusable states like Shutdown and Conversion Rate.
3. Registers: The memory map linking addresses to bit-fields and enums.

This YAML file is now ready to be fed into ChipLib to generate your C++, Python, or any other library!