Other Parts Discussed in Thread: CONTROLSUITE, TMS320F28388S, TMS320F28379D, , BOOSTXL-POSMGR
Hi Team,
We would like to ask your help regarding our customer's inquiry below.
I am currently developing a TMS320F28388 custom board to control 2 3-Phase GaN PMSM driver featuring Ethernet/CAN/I2C and 4 ports for multiprotocol external encoders (SinCos/BiSS/SSI/EnDAT/Resolver/Incremental). While working on the encoder interfaces. Your TIDUE73 (April 2018) got my attention. This document describes an elegant way to compensate for the propagation delay occurring in BiSS/EnDAT lines. As described on p7. Figure 5 the CLB is used to generate a delayed clock and feed the SPI slave module.
However, this application note doesn’t tell how many CLB tiles are used, nor if it is possible to use more than one interface with your library. From p6. Figure 4, I made the assumption that up to 3 BiSS-C encoders can be used simultaneously. As the TMS320F2837x has 8 tiles, this may suppose that each BiSS interface uses 1 or 2 tiles. However, the information isn’t given.
By looking at the source code, I can see from : C:\ti\controlSUITE\libs\app_libs\position_manager\v01_02_00_00\bissc\examples\PM_bissc_SystemTest that 4 CLB Tiles are configured. However, the code isn’t clear how the C2000 Position Manager BISS-C Library uses these CLBs and how they are configured.
From the E2E forums, I’ve got some relevant information. You will find the summary at the bottom.
I would like to answer the following questions:
- The BiSS/EnDAT library is currently only available for TMS320F2837x and for one encoder only despite the fact the TIDUE73 mention that several BiSS encoders can be used. Are you planning to release a more customizable version of that library that runs on a 28388 and accept more than one encoder?
- On the E2E forum, I can read that a library release potentially involving the BiSS encoder library will be released with the new SDK in June 2022. Is that correct? Do you know what will be released?
- It is not clear what CLB the BiSS/EnDAT libraries are using. Could you please confirm the following?
-
- The BiSS Position library uses 1 PWM (ePWM4), 2 CLB tiles (3 and 4), 1 SPI
- The EnDAT Position library uses 2 PWM(ePWM3 and 4), 3 CLB tiles (3, 4 and ?), 1 SPI
Here below that I’ve read from the E2E forum.
Currently EnDat22 and BiSS-C are not yet available with new CLB tool and complete source code.
These are planned to be released later this year.
Current libraries for BiSS-C are available for the F28379D only. Also, these libraries can be used to connect to 1 encoder only. There is no internal switch to switch between encoders or to support more than one encoder at a given time.
The library for BiSS-C may not work for SSI interface. The library has predefined functionality and can not be modified.
We are working on a separate library for SSI interface. Please watch the www.ti.com/c2000drives page for updates.
We are planning on releasing a version for the F28388x with software source available later this year but I do not have a definite date.
TMS320F28388S: Whether it is support ENDAT2.2 for CLB library ?
TMS320F28379D: biss-c init setting. On this device the CLB is clocked by the same clock as the PWM. Since CLB Tile 3 is used, ePWM3 clock is enabled.
A BiSS instance uses 2 CLB tiles. In the example library it uses Tile 3 and Tile 4. This has some influence over the pins uses (see ePWM4A/B selection below)
ePWM4A/B.
Tile 4 output 0 is able to override ePWM4A and Tile 4 output 2 can override ePWM4B outputs - these were chosen as it was convenient and the trip functionality could be leveraged to set the initial value.
Note: this changes based on tile # - Tile1 can override ePWM1A/B, Tile2 ePWM2A/B etc up to 4. Refer to the CLB chapter of the device-specific Technical Reference Manual (TRM) for connection capabilities.
EPWM4B has to be tied to the SPICLK of the SPI instance being used. In this case SPIB. The CLB drives this clock.
GPIO9 is a GPIO accessed by the CLB via the OUTPUTXBAR. CLB output 4 and output 5 (on any tile) can be connected to the OUTPUTXBAR. In this case it is Tile 3 accessing this. Refer to the CLB TRM chapter.
TMS320F28388D: Biss-C availability Unfortunately we are looking at June 2022 timeframe for an SDK release.
https://www.ti.com/tool/TIDM-1008
TI library consumes 3 tiles for EnDat and 2 tiles for BiSS-C and 1 for T-format
Tiles 2, 3 and 4 are used all the time.
Tile 1 is used, but only initially, until the delay compensation measurements for the cable length are complete.
Therefore, tile 1 config can be overwritten with a different configuration to handle the PTO after the delay compensation has completed.
Regards,
Danilo
