Using the memory access gives the possibility to:
- Get information about which memories are available
- Read/write/erase memories
Currently the following memories are supported:
- Crazyflie 2.x onboard EEPROM
- Crazyflie 2.x expansion board 1-wire memories
There's more information available for how the EEPROM is structured and how the 1-wire memories work and are structured.
Logical flow
Getting information and reading/writing the memories is optional for the clients, but the -Crazyflie Python Client- always downloads information about the memories on connect.
Communication protocol
The memory port uses 3 different channels:
Port Channel Function ———- ————- ——————————————————————— 4 0 Get information about amount and types of memory as well as erasing 4 1 Read memories 4 2 Write memories
Channel 0: Info/settings
This channel is used to get the number of memories present, information about the memories and the possibility to mass erase memories. The first byte of every packet is a command byte:
| Command byte | Command | Operation |
|---|---|---|
| 1 | GET_NBR_OF_MEMS | Get the number of memories |
| 2 | GET_MEM_INFO | Get information about a memory |
| 3 | SET_MEM_ERASE | Mass erase a memory |
GET_NBR_OF_MEMS
This command is used to get the number of memories present.
The request from host to Crazyflie:
| Byte | Field | Value | Length | Comment |
|---|---|---|---|---|
| 0 | GET_NUMBER_OF_MEMS | 0x01 | 1 | The command byte |
Reply from Crazyflie to host:
| Byte | Field | Value | Length | Comment |
|---|---|---|---|---|
| 0 | GET_NUMBER_OF_MEMS | 0x01 | 1 | The command byte |
| 1 | Number of memories | 1 | The number of memories preset (all types) |
Example where there are 3 memories present on the Crazyflie:
Host-to-Crazyflie: <port/chan> 0x01
Crazyflie-to-Host: <port/chan> 0x01 0x03
GET_MEM_INFO
This command is used to get information about a memory give it's id. The id of memories is sequential and is from 0 to one less than the returned number of memories from GET_NUMBER_OF_MEMS.
The request from host to Crazyflie:
| Byte | Field | Value | Length | Comment |
|---|---|---|---|---|
| 0 | GET_MEM_INFO | 0x02 | 1 | The command byte |
| 1 | MEM_ID | 1 | A memory id that is 0 <= id < NBR_OF_MEMS |
Reply from Crazyflie to host if the id is valid:
| Byte | Field | Value | Length | Comment |
|---|---|---|---|---|
| 0 | GET_MEM_INFO | 0x02 | 1 | The command byte |
| 1 | MEM_ID | 1 | The memory id | |
| 2 | MEM_TYPE | 1 | The memory type (see below) | |
| 3 | MEM_SIZE | 4 | The size in bytes of the memory | |
| 7 | MEM_ADDR | 8 | The address of the memory (only valid for 1-wire memories) |
Where the MEM_TYPE field is:
| MEM_TYPE | Memory type | Comment |
|---|---|---|
| 0 | I2C | |
| 1 | 1-wire |
Reply from Crazyflie to host if the id is not valid:
| Byte | Field | Value | Length | Comment |
|---|---|---|---|---|
| 0 | GET_MEM_INFO | 0x02 | 1 | The command byte |
| 1 | MEM_ID | 1 | The memory id |
Example of requesting the information for a 1-wire memory with MEM_ID=1, MEM_SIZE=112bytes, MEM_ADDR=0x1234567890ABCDEF
Host-to-Crazyflie: <port/chan> 0x02 0x01
Crazyflie-to-Host: <port/chan> 0x02 0x01 0x01 0x70 0x00 0x00 0x00 0xEF 0xCD 0xAB 0x90 0x78 0x56 0x34 0x12
Example of requesting the information for a memory index that is not valid
Host-to-Crazyflie: <port/chan> 0x01 0x10
Crazyflie-to-Host: <port/chan> 0x01 0x10
SET_MEM_ERASE
This command is used to mass erase a memory with a given id. The id of memories is sequential and is from 0 to one less than the returned number of memories from GET_NUMBER_OF_MEMS.
The request from host to Crazyflie:
| Byte | Field | Value | Length | Comment | |
|---|---|---|---|---|---|
| 0 | SET_MEM_ERASE | 0x03 | 1 | The command byte | |
| 1 | MEM_ID | 1 | A memory id that is 0 <= id < | NBR_OF_MEMS |
Reply from Crazyflie to host:
| Byte | Field | Value | Length | Comment |
|---|---|---|---|---|
| 0 | SET_MEM_ERASE | 0x03 | 1 | The command byte |
| 1 | MEM_ID | 1 | The memory id | |
| 2 | STATUS | 1 | The status of the command (see below) |
Example of requesting a mass erase for a memory with MEM_ID=2
Host-to-Crazyflie: <port/chan>
Crazyflie-to-Host: <port/chan>
Example of
Host-to-Crazyflie: <port/chan>
Crazyflie-to-Host: <port/chan>
Channel 1: Memory read
This channel is only used to read memories and therefore the messages do not contain any command byte.
The request from host to Crazyflie:
| Byte | Field | Value | Length | Comment |
|---|---|---|---|---|
| 0 | MEM_ID | 1 | A memory id that is 0 <= id < NBR_OF_MEMS | |
| 1 | MEM_ADDR | 4 | The address where the first byte should be read | |
| 5 | LEN | 1 | The number of bytes to be read |
Reply from Crazyflie to host if memory id is valid and the address and length to be read is valid:
| Byte | Field | Value | Length | Comment |
|---|---|---|---|---|
| 0 | MEM_ID | 1 | A memory id that is 0 <= id < NBR_OF_MEMS | |
| 1 | MEM_ADDR | 4 | The address where the first byte should be read | |
| 5 | STATUS | 1 | The status of the request (see below) | |
| 6 | DATA | 1..24? | The data that was read (only if MEM_ID/MEM_ADDR/LEN is valid) |
Where the STATUS field is:
STATUS Comment ——– ——— 0 ... 1 .…
Example of reading LEN=0x0F bytes from MEM_ID=0x01 MEM_ADDR=0x0A
Host-to-Crazyflie: <port/chan> 0x01 0x0A 0x00 0x00 0x00 0x0F
Crazyflie-to-Host: <port/chan> 0x01 0x0A 0x00 0x00 0x00 0x00 0x01 0x09 0x62 0x63 0x4C 0x65 0x64 0x52 0x69 0x6E 0x67 0x02 0x01 0x62 0x55
Channel 2: Memory write
This channel is only used to write memories and therefore the messages do not contain any command byte.
The request from host to Crazyflie:
| Byte | Field | Value | Length | Comment |
|---|---|---|---|---|
| 0 | MEM_ID | 1 | A memory id that is 0 <= id < NBR_OF_MEMS | |
| 1 | MEM_ADDR | 4 | The address where the first byte should be read | |
| 5 | DATA | 1..24? | The data to be written |
Reply from Crazyflie to host if memory id is valid and the address and length to be written is valid:
| Byte | Field | Value | Length | Comment |
|---|---|---|---|---|
| 0 | MEM_ID | 1 | A memory id that is 0 <= id < NBR_OF_MEMS | |
| 1 | MEM_ADDR | 4 | The address where the first byte should be read | |
| 4 | STATUS | 1 | The status of the request (see below) |
Where the STATUS field is:
| STATUS | Comment |
|---|---|
| 0 | ... |
| 1 | .… |
Example