APGRD004 Microchip Technology, APGRD004 Datasheet - Page 17

• Manufacturer Part Number: APGRD004
• Description: REF DESIGN MOD AUTO AMBNT LIGHT
• Manufacturer: Microchip Technology

Specifications of APGRD004

• Main Purpose: Lighting, RGB LED Controller
• Embedded: Yes, MCU, 8-Bit
• Utilized Ic / Part: MCP2021, PIC12F615
• Primary Attributes: 4 Tiny Boards, Each Have: RGB LED, LIN Transceiver, Voltage Regulator, MCU
• Secondary Attributes: LIN Commands are Interpreted to Control 16,383 Colors and 1,023 Dimming Levels
• Silicon Manufacturer: Microchip
• Silicon Core Number: APGDT001
• Kit Contents: 4 Ambient Lighting Modules, Documentation
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

DS51714A-page 13
Interior Ambient Lighting Module with LIN Interface User’s Guide
3.1.3.2
Register 3-8 lists the status request frame format.
REGISTER 3-8:
The response to a status request is four bytes followed by a checksum. The four bytes
returned are not defined by this version of code.
3.1.4
The LIN handler routine is illustrated in Figure B-1. This code includes:
• LIN 2.0 compatible slave interface
• USART function is software-based (bit-bang)
• Break characters are detected and validated for length
• Baud rate is measured and the register values are calculated based on the
If either the Break or Sync character causes an error, or the identifier is not listed in the
table, an error condition is flagged.
With a valid Break Sync header, the process of the LIN handler routine continues:
1. The identifier byte is passed through an ID look-up table to check applicability to
2. The message length is extracted from the look-up table.
3. The look-up table supplies a bit to determine whether this message data field is
4. The received data is stored in a buffer.
5. The identifier parity bits and the message frame checksum are checked.
Or:
4. The transferable data is taken from the buffer and transmitted.
5. The appropriate checksum is generated.
3.1.4.1
Some enhancements that can easily be implemented to the LIN handler:
• Although various types of errors are detected, none are accumulated.
• Transmitted data bit testing is not done.
• The usage of the internal timer/counter to determine bus time-out and Idle
bit 7-6
bit 5-0
incoming Sync character
- For additional error reporting, error counters could be added.
- This could be added at point ‘A’ marked in the LIN handler flowchart. Bus
conditions.
bit 7
this slave.
supplied or will be consumed.
errors, thus detected, can be accumulated and reported.
1
Parity
STATUS REQUEST FRAME
LIN Slave Protocol Handler
PROPOSED SOFTWARE ENHANCEMENT
Parity: As Defined in the LIN Specification
ID Number: Ambient Light Status ID 0x24
bit 6
0
STATUS REQUEST
bit 5
1
bit 4
0
bit 3
0
ID Number
bit 2
© 2008 Microchip Technology Inc.
1
bit 1
0
bit 0
0