1. Introduction
The acquisition rate can be an important parameter if someone wants to monitor values changing quickly. The time required to retrieve the data value from the target can be influenced by many parameters. The purpose of the article is to explain which parameters should be checked and how to get best performances.
STM32CubeMonitor variable monitoring STM32CubeMonitor performs data acquisition by reading in the target MCU memory though ST-Link and SWD/Jtag connection. Elements involved are :
- STM32 MCU debug bloc which performs access to the memory through MCU bus.
- STM32 JTAG/SWD access port, used to connect the
- ST-Link device
- USB connection on the computer
- STM32CubeMonitor software
[[Image:installation_1welcome.png.png |
2. Acquisition speed setting in STM32CubeMonitor
The acquisiton frequency can be set in the variable node. If many variable nodes are used, different speed can be set for each node. It is possible to have variable refreshed very quickly, while others are refreshed at lower rate. The setting "sequential loop" provides the fastest acquisition rate : as soon as a measurement is complete, a new one is started.
3. Elements impacting acquisition time
3.1. ST-Link speed
3.2. USB latency
3.2.1. Computer performances
slow computer = slow speed
3.2.2. Use of ST-Link server
stlink server adds delay
3.3. Data size and location
the size and locaiton impacts a lot
3.3.1. size
bigger = slower
3.3.2. location vs optimisation
explain optim algorithm and impact o performances
4. Snapshot mode
In snapshot, the frequency is the frequency to dumlp data from the target, but the acquition rate can be higher . Explain more...
5. Typical performances
put some figure measured on our ref config
6. Conclusion
conclude here