AN2442 Freescale Semiconductor / Motorola, AN2442 Datasheet - Page 8

• Manufacturer Part Number: AN2442
• Description: Booting the MSC8102 Device Through TDM
• Manufacturer: Freescale Semiconductor / Motorola

Perform the Block Transfer of Code and Data
4.2 Block Transfer Acknowledge Message
8
The BTAM is the message that the slave MSC8102 sends back to the boot master. It contains information
about the previously received BTM (see Table 3).
The MSC8102 slave device implements a logic layer protocol to receive data and ensure correct
transmission from the boot master device. Figure 7 shows the flow diagram of the logic layer protocol,
which works as follows:
1. The MSC8102 synchronizes with the preamble (PRM) field of the BTM.
2. If there is an error in the CRC-16 of the header (HCRC), then return to step 1. Otherwise, continue to
3. If the destination CHIP_ID (DCID) is equal to the MSC8102 CHIP_ID or if it is equal to 0xFF for a
4. If the CRC-16 of the payload (CRC) contains no error, the MSC8102 device sends a BTAM with its
5. If the expected sequence number of the next message (RN) is equal to the sequence number of the
6. If the end block (EB) flag has a value of 0xFF, the TDM boot session ends. Otherwise, return to step
Size (Bytes)
the next step.
broadcast message, then the payload data (PLD) is written to the destination address (DA). Other-
wise, return to step 1.
CHIP_ID in the SCID field and the receive sequence number (RN). Otherwise, continue to the next
step.
current message (SN), then the MSC8102 device sends a BTAM with an RN and SCID with its
CHIP_ID. Otherwise, the RN is incremented and the MSC8102 device sends a BTAM with the
updated RN and SCID with its CHIP_ID.
1 to continue with the next BTM.
2
1
1
2
Block Transfer Message
Freescale Semiconductor, Inc.
For More Information On This Product,
Table 3. Block Transfer Acknowledge Message Structure
Name
APRM
ACRC
SCID
RN
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0x00 to 0xFF
CHIP_ID
0x6655
Value
Preamble. Indicates the start of the acknowledge message.
First byte sent is 0x55.
Source CHIP_ID. Identifies the target MSC8102 slave device
that accepted the BTM.
Receive Sequence Number modulo 256. Indicates the
expected sequence number to receive next.
CRC-16 of APRM, SCID and RN. EB = 0xFF indicates the
last BTM. After the last message, all SC140 cores jump to
address 0x0 of their M1 memory.
Description