tm4c129x and bulk transfer and device

Hi,

  I think it is possible. However, we don't have a bulk transfer example for host but only for device. Let us know if you can get it to work and share your tips with the community. If you need further assistance then I will need to forward your question to our USB expert but the response probably won't happen until next week though.   

  Below posts may be also helpful. 

https://e2e.ti.com/support/microcontrollers/other-microcontrollers-group/other/f/other-microcontrollers-forum/854577/tm4c1294kcpdt-does-tivaware-support-host-cdc-driver/3161179?tisearch=e2e-sitesearch&keymatch=usb%2525252520host%2525252520cdc#3161179

https://e2e.ti.com/support/microcontrollers/other-microcontrollers-group/other/f/other-microcontrollers-forum/734482/tm4c1294nczad-file-transfer-via-usb/2711940?tisearch=e2e-sitesearch&keymatch=usb%25252525252525252520host%25252525252525252520bulk%25252525252525252520transfer#2711940

https://e2e.ti.com/support/microcontrollers/other-microcontrollers-group/other/f/other-microcontrollers-forum/992166/ek-tm4c1294xl-ek-tm4c1294xl-usb-msc-host/3665225?tisearch=e2e-sitesearch&keymatch=usb%2525252525252520host%2525252525252520bulk%2525252525252520transfer#3665225

Thanks for the info.. Question, if I may, There is a lot of different models defined. I have a special requirement that may require two Tm4c129x to share data at a high rate. Processor are on the same board and control different device (not via USB, need to be a small footprint). Therefore, DPM/RAM is one way, however, more board space required. USB provides a simple data share at 12Mbs. i Don't have much experience in USB data transfer. Would bulk or CDC be a better method to use to share data using DMA? Any thoughts or example to point at a starting point?   

robert bond said:

Therefore, DPM/RAM is one way, however, more board space required.

Sorry, for what is DPM?

robert bond said:

Would bulk or CDC be a better method to use to share data using DMA?

 The CDC class also makes use of the bulk transfer. The USB endpoint can be configured for 4 different types of transfers - control, isosychronous, interrupt and bulk. The CDC class uses bulk transfer. 

DPM "dual port memory"..  CDC I saw that but have not look closely enough at it. is there an host/device examples? Since what I'm doing is just mem transfer of data. I've been playing with msc both host and device side. I'm currently working on reconfiguring the size and number of block to scale it down on both ends (bytes of X len or bytes at a fixed transfer size). Simply meaning, make the device side not see the flash chip but rather point to a memory location in the processor. So far everything from connect to disconnect seem fine. However, still looking into where are the hard defines for block/sector and size are located in the lib files. 

Simple look at application (still working on single tm4c129x processor approach, two is a backup plan):

I need one processor to collect data at a very high rate (SPI 9Mhz) and store it locally. once done transfer it to the second processor and resume collecting, The second processor  collects other data (not high data rate) and then puts it on the network. memory sharing or DPM is a better way, however board size must be small. High speed processors require more external real estate than two of the TM4c129x + they can share power, clk and rst logic....

Question: I know CDC example seems to be pointing a Uart/serial example. where baud rate set at 115.2K. I need to run data stream at 12Mbits (USB 1.1, full speed)

 forget question- can serial app run at fast data rate and is my understanding correct on the CDC example?

Hi Robert,

  I will forward your question to our USB expert. 

Thanks! really appreciate it

Hi Robert,

I will try and pull some information about general USB throughputs together for you tomorrow, I recall there are some documents that go over what to expect from different interfaces.

Best Regards,
Ralph Jacobi

Thanks.. any help would be great and any host code will help too

Any updates on gathering the USB info?

Hi Robert,

I hadn't been able to find the resources so let me step back and really get back to the root questions here. Generally CDC is considered the fastest option for burst data transfers and tends to be the go to for higher speed data transfers with USB. Some people try and define custom protocols to use isochronous transfers for the larger packet size but I haven't seen that done on TM4C. Usually isochronous is used to periodically send large data packets such as for audio.

While it doesn't go into USB modes per say, this overviews the different transfer types that are available: https://www.beyondlogic.org/usbnutshell/usb4.shtml

Now one of the reasons I was trying to find that throughput resource is because it actually calculates out maximum theoretical throughput based on the 12Mbs interface while accounting for protocol overhead. I'm going to be drawing from memory here so don't treat this as gospel but I recall the actual effective data rate tops out at ~8Mbs.

For our TM4C microcontrollers, when in device mode we've seen usually about 600-800kB/s (Note this Bytes now, not bits), but I have not seen any specs for host mode. I don't expect a large delta on that front in either direction.

robert bond said:

Question: I know CDC example seems to be pointing a Uart/serial example. where baud rate set at 115.2K. I need to run data stream at 12Mbits (USB 1.1, full speed)

That is just how our demonstration is setup for TivaWare to make a simple example program. There is no requirement to do this what so ever and pretty much every application does USB to USB to get the higher speeds.

robert bond said:

any help would be great and any host code will help too

I do have a USB Host CDC example for our EK-TM4C1294XL LaunchPad but it hasn't been entirely finalized yet. I can see about providing that, but will be clear it comes 'as is' for now. Our plan is to finalize that and release later this year, but I haven't restarted on that activity yet and would not be able to do so in the next couple weeks.

I have been unfortunately struggling to carve out time to test that out which is why I was so delayed in my reply here but let me see what I can do to get that done tomorrow so I can provide that for you to start tinkering with. I need to see if I had the LaunchPad to LaunchPad transfer working too or if it was just LaunchPad to PC.

Best Regards,

Ralph

Thanks Ralph..  I don't need to transfer large data (only 3K) just needs fast and  between data collection interrupt. any code you can share would be great. I was looking at bulk but the example only do device and it looks like a lot of work to create a bulk host example (looks like lib changes to support it). That why  switch to MSC and seems I just need to change the sector/bulk and bytes to get that to possible work (lib change - I think small though)..

Any thoughts down that road?

Rob

Hi Robert,

robert bond said:

fast and  between data collection interrupt

If you want it to be driven like this, CDC is the way to go.

The USB CDC Host example I'd provide will come with new usblib files generated to support that. I've got time carved off this afternoon to work on providing that.

Best Regards,
Ralph

Thank you show much, really apricate it

Rob

Hello Robert,

While enumeration is working, I don't have data transfer working right now between the examples. I need to debug that further on Monday. I know it had been at one point so should be quick to resolve but need to hook up the USB analyzer and reacquaint myself with the protocol.

Best Regards,

Ralph

Sweet! once again thank you for ur help!

Hello Robert,

I was not able to fix issue today. I will probably need most of the week to get this sorted back out as I haven't delved into the protocol in a long time and I want to make sure its done right. Expect the next update late on Thursday - any sooner probably means I solved it.

Best Regards,

Ralph

no problem.. Any help is great..

Thanks

rob

Thanks Ralph!  I'll start this later today!!