M-Link Link Layer
Control Codes
RX_DV/TX_EN |
RX_ER/TX_ER |
description |
0 |
0 |
IDLE (< K28.5, D5.6 >, < K28.5, D16.2 >) |
0 |
1 |
CE, Carrier extend (K23.7, K23.7) |
1 |
0 |
ND, Normal data character (DX.Y) |
1 |
1 |
EP, Error propagation (K30.7, K30.7) |
Reset frame: IDLE, CE, CE, CE, CE, CE, IDLE.
Link Control frame: IDLE, CE, CE, CE, ND, ND, IDLE.
Data frame: IDLE, CE, ND repeated even times, IDLE.
Any other sequence should not be decoded. It should not block the connection. Erroneous character sequences are recommended to be counted and reported.
Link Control Frame
Link Control frame data is transferred in two 16-bit words, first is control word, second is the bit inversion of the control word for error protection. On receive side, the control word should be analyzed only if the second word is the exact bit inversion of the first word.
bit |
description (send) |
action on receive side |
0 |
Suspend (receive buffer is full) |
Stop transmitting data |
1 |
Enable remote loopback |
Enable loopback mode |
2 |
Local Spill signal |
Remote Spill state |
3 |
Local Error state |
Remote Error state |
4 |
Local Ready state |
Remote Ready state |
15:5 |
0 |
Must be 0 |
31:16 |
Inverted 15:0 |
Must be equal to inverted 15:0 |
Link Control Frame (LCF) must be sent continuously every T us (*) after reset independently on any other frames. LCF has highest priority. If no LCF is received after 5*T time, link is considered down.
(*) – repetition interval may be programmed. Default is 1000 μs.