Lab #4 Reading and Writing to Super Stepper Memory
Introduction:
After this lab, the user will have gathered basic knowledge on how to read and write the internal RAM and EEPROM memory locations found on all Super Stepper control modules. Knowing how to modify such resources allows the user to configure the module to their own particular needs.
Objectives:
- To read EEPROM and RAM memory from the Super Stepper control module.
- To write data to the EEPROM and RAM memory on the Super Stepper control modules.
Why is there memory in the Super Stepper Controller?
The Super Stepper control modules contain a series of memory resources intended for flexibility. Per example, it is at this time known that there can be up to 32 devices connected to the same serial port since every module contains a different address which identifies it from the other 31. This address parameter is stored in EEPROM memory. After reset, the address stored in EEPROM is transferred to its pertinent register in the controller operating system.
Other important Super Stepper parameters are baud rate. Again, this parameter is stored in EEPROM and after reset transferred into a pertinent register in the OS.
Application specific parameters are those which are required by the application to properly function. Per example, the SS-ST68 contains a few memory bytes utilized for programming initial speed, acceleration rate, acceleration time base, etc. These parametes should be studied on the particular application controller data sheet.
Not all memory in the controller is used for specific functions. Most of the space is left for the user as a general purpose scratch pad. Most users will find this resource useful for application personalization and limited data storage.
In this tutorial we will learn how to access the memory in the controller both by reading and writting it.
Reading the EEPROM and RAM Memory
All Super Stepper Controllers contain 128 bytes of EEPROM and 64 bytes of RAM. There is a SS Command to read these memory locations. The same commands knows how to differentiate RAM from EEPROM by means of one of the command parameters. We need to know this as in the Windows application, one of the parameters must be specified in order to select RAM from EEPROM. Future releases will make this totally transparent for the user.
- Open the Super Stepper Test Aplication
- Connect the board as learned, power up, configure the port and Connect
- Make sure everything is working by executing one of the already known commands (i.e. “Move CW”).
- Open Boards->Stepper
- On the “Stepper Instructions (for Advanced Users)” pull down list select “Read EEPROM”. The program generates the operands as needed for such operation (notice the second text box label reads “RD EEPROM”)
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- On the address text box specify the EEPROM address (from 0 to 127) you wish to read. Reading address 0 should return the BAUD Rate stored in memory.
- Press the “Send Data” button.
- The “Super Stepper Architecture Tester” window should contain what the SS module returned. From the 5 bytes, the third one contains the returned data (Refer to the Architectural data sheet for more information on what the five returned bytes stand for).
The previous steps are identical for when reading from RAM memory. Just select the “Read RAM” from the pull down menu on the “Stepper Instructions (for Advanced Users)” frame and choose the address to read.
Notice the second text box label reads “RD RAMB” for Read RAM Byte. This text box contains a “0” while when we where reading EEPROM it contained a 1. That is how the controller differentiates an EEPROM read from a RAM read.
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Writing the EEPROM and RAM Memory
Writting to RAM or EEPROM is a different matter, because now we must specify not only the address but the data to be written as well. The instruction follows:
- On the “Stepper Instructions (for Advanced Users)” pull down list select “Write EEPROM”. The program generates the operands as needed for such operation (notice the second text box label reads “WR EEPROM”)
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- Specify the address and the data on the respective “Address” and “Data” text boxes. Use a 1 for the address and a 5 for the data.
- Press the “Send Data” button.
- The “Super Stepper Architecture Tester” window should contain what the SS module returned. In this case it matters little what it returned since the data was sent to the controller not from it. Of course it is important to know whether the operation took place correctly and learning how to read the five bytes is recommended. Check the Architectural data sheet for more information.
Writting to RAM consist of the same set of steps but choosing “Read RAM” from the pull down list. Again notice that the WR RAMB text box contains a 0 instead that a 1 for the WR EEPROM text box. This parameter is used to specify RAM or EEPROM access and the Windows application takes care of this detail making it transparent to the user.
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Reading Multiple EEPROM and RAM Bytes
The Super Stepper Test Application contains a tool to read memory in a faster way. Basically the entire RAM and EEPROM bank can be read with a single stroke. The application reads all bytes one by one using the same commands we just learned how to use. Then, the five byte data stream returned is parsed to obtain the read byte. All bytes read are displayed on a single text box making it easy to sample the entire memory contents.
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- On the “Super Stepper Architecture Test window select Tools->Memory. The “Memory Read” window opens.
- Select either “Read EEPROM” or “Read RAM” from the pull down list.
- Press the “Capture Memory” button.
That’s all you need. It would be nice to have a tool to write all bytes at the same time, but that is just a feature we will be developing in the future.
Congratulations!!! You have successfully completed the fourth lab on the Super Stepper Architecture. You are now capable of reading and writing data from and to the memory inside the super stepper controller module.
Hungry for more? Next topic is EEPROM Programming!
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Last Updated on Jan 10, 2008
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