Memory management and upload protocol
M210 device save notes in flash memory.
Each note contain note header and data (XY coordinates, Pen up)
Note structure description:
Note header: 14 Bytes.
Byte number | Byte description | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
1 | Pointer to next note address | Low | |||||||
2 | |||||||||
3 | High | ||||||||
4 | Flags | Note open | Note closed | Note closed (software) | 1 | 1 | 1 | 1 | 1 |
5 | Note number | ||||||||
6 | Total note number | ||||||||
7 | Reserved | ||||||||
8 | |||||||||
9 | |||||||||
10 | |||||||||
11 | |||||||||
12 | |||||||||
13 | |||||||||
14 | |||||||||
Note open:
0 – There is XY coordinates in this note.
1 – Empty note.
Note closed:
0 – The note closed by user or software.
1 – Note not closed.
Note closed (software):
0 – Note not closed by user.
1 – else.
Data:
XY coordinates: 4 Bytes
Byte number | Byte description | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
1 | X coordinate | Low | |||||||
2 | High | ||||||||
3 | Y coordinate | Low | |||||||
4 | High | ||||||||
Pen up: 4 Bytes
Byte number | Byte description | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
1 | Pen up | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
2 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
3 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
4 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
Memory data structure example:
Note 1 header | XY | XY | XY | XY | …. | Pen up | XY | XY |
XY | Pen up | Note 2 header | XY | …. | Pen up | Note N header |
Remark:
1. The last note will be empty note and the pointer for next note = 0xFFFFFF
Upload:
Upload data from device memory.
Upload Sequence:
Request start of upload
Host Device
Upload Command (1 Byte) |
0xB5 |
Device sends the number of data packets to host.
Device Host
Signature (5 Bytes) | Number of packets (2 Bytes) | Signature (2 Bytes) | ||||||
0xAA | 0xAA | 0xAA | 0xAA | 0xAA | High | Low | 0x55 | 0x55 |
Host sends an ACK for receiving the data packets or NACK for cancel upload to device.
Host Device
ACK (1 Byte) |
0xB6 |
NACK (1 Byte) |
0xB7 |
Device sends upload data to host.
Device Host
Packet number (2 Bytes) | Data (62 Bytes) | |
N | Upload Data | |
High | Low | |
N – Sequence number, each packet gets a sequence number(starting with 1), e.g. the first packet gets sequence number 1, the second 2 etc..
Upload Data – Data of all notes (header and data) from memory.
e.g. packet number 1 will contain data form address 0 to 61 in the memory, packet number will contain data form address 62 to 123 in the memory etc.
Packets retransmission.
Host Device
5.a. In case all packets have been received successfully, the host sends an ACK
response and the upload sequence is complete.
ACK (1 Byte) |
0xB6 |
5.b. In case some packets have been lost the host sends a NACK response with
the lost packet number.
NACK (1 Byte) | Lost packet number (2 Byte) | |
0xB7 | X | |
High | Low | |
X – Lost packet number.
Device send the lost packet to host (return to stage 5).
Device Host
Packet number (2 Bytes) | Data (62 Bytes) | |
X | Upload Data | |
High | Low | |
X – Lost packet number.