FireWatchTower_2axis/firmware/lib/tmc/ic/TMC7300

TMC7300

How to use

To access the TMC7300's registers, the TMC-API offers two functions: tmc7300_readRegister and tmc7300_writeRegister. Each of these functions takes in an icID, which is used to identify the IC when multiple ICs are connected. This identifier is passed down to the callback functions (see How to Integrate).

How to integrate: overview

1. Include all the files of the TMC-API/ic/tmc/TMC7300 folder into the custom project.
2. Include the TMC7300.h file in the custom source code.
3. Implement the necessary callback functions (see below).
4. (optional): Take a look at the Examples subfolder for ready-made examples of the TMC-API usage.

Accessing the TMC7300 via UART

The following diagram depicts how to access the TMC7300 via UART using the TMC-API.

The description of the functions, in the above flowchart, are as follows:

• The functions tmc7300_readRegister and tmc7300_writeRegister are used to read and write the registers respectively. These functions check the current active bus and calls the bus-specific function i.e readRegisterUART or writeRegisterUART.
• These bus specific functions constructs the datagram and further calls the bus specific callback 'tmcXXXX_readWriteUART.
• This callback function further calls the hardware specific read/write function for UART and needs to be implemented externally.

How to integrate: Callback functions

To communicate with TMC7300 IC, the TMC-API library needs to know which bus (UART) it shall use. Additionally, implement the following callback functions to access the chip via UART:

1. tmc7300_readWriteUART(), which is a HAL wrapper function that provides the necessary hardware access.
2. tmc7300_getNodeAddress(), that returns the node/slave address. Node address could be set in NODECONF (0x3) register and the address could be incremented as defined by AD0, AD1 and AD2. (Node address + ADx) must be less than 255. For further details please consult the datasheet of TMC7300.

Sharing the CRC table with other TMC-API chips

The TMC7300 UART protocol uses an 8 bit CRC. For calculating this, a table-based algorithm is used. This table (tmcCRCTable_Poly7Reflected[256]) is 256 bytes big and identical across multiple different Trinamic chips (i.e. TMC7300). If multiple Trinamic chips are being used in the same project, avoiding redundant copies of this table could save memory. It is possible to substitute this CRC table with another CRC table.

Option to use the cache logic for Write-Only registers

The chip features write-only registers that are unable to be read, necessitating the creation of a shadow copy to cache their contents. This copy is automatically updated whenever data is written to these registers. This cache logic could be enabled by setting the macro TMC7300_CACHE to '1' or disabled by setting to '0' respectively. If this feature is enabled then there comes another option to use tmc7300_cache function, which is already implemeted in the API, by defining TMC7300_ENABLE_TMC_CACHE macro to '1 or one can implement their own function. The function tmc7300_cache works for both reading from and writing to the shadow array. It first checks whether the register has write-only access and data needs to be read from the hadow copy. On the basis of that, it returns true or false. The shadowRegisters on the premade cache implementation need to be one per chip. TMC7300_IC_CACHE_COUNT is set to '1' by default and is user-overwritable. If multiple chips are being used in the same project, increment its value to the number of chips connected.

Further info

Dependency graph for the ICs with new register R/W mechanism

This graph illustrates the relationships between files within the TMC-API library, highlighting dependencies and identifying the files that are essential for integrating the library into the ustom projects.

Example usage: TMC-Evalsystem

For a reference usage of the TMC-API, visit the TMC-Evalsystem

Migration status

The TMC7300 has been reworked to the access system described above. For more infos on the status of this and other ICs, check out the migration page.