LPC11u37h usb DEVCMDSTAT register.. cannot change the DEV_ADDR bits...

[lpcware]

Content originally posted in LPCWare by siangming on Wed Dec 10 23:26:05 MST 2014
Hi all,

i am trying to implement a simple USB device on the lpc11u37h.

i am writing my own device drivers on the lpc, but my program got stuck at the Set Address request from the host PC (win 7).

1. i am getting a valid new address from the host.
2. i am writing the new address into DEVCMDSTAT register inside the ISR of the endpoint0 IN interrupt (which correspond to the STATUS stage completion). i know for sure that i am writing the new address in the STATUS stage completion because i set a flag during the SETADDRESS request handling and check for this flag in my endpoint0 IN ISR before i proceed to set the new address.

Here comes the problem.. upon inspection of the register values, i realised i cannot write to the DEV_ADDR (bit0..6) of the DEVCMDSTAT.

ptrToUSB->DEVCMDSTAT |= 0x7F; has no effect on the last 7bits of the register.

- To investigate further, i loaded an example USB HID application by NXP into my LPC chip and it can enumerate ok on the same host pc. This proves my LPC hardware is ok.
- Next, i tried to write to the DEV_ADDR (bit0..6) of the DEVCMDSTAT at the beginning of my program (just after reset_handler)..i also cannot change the bit0..6 at all.. but i can change the other bits of the DEVCMDSTAT register...

Can anyone advise if the LPC11u37h is hard-wired such that we need to satisfy some conditions/settings in some registers before we can write to the DEV_ADDR (bit0..6) of the DEVCMDSTAT??

i am so lost.... HELP!!!

[lpcware]

Content originally posted in LPCWare by siangming on Thu Dec 11 19:32:34 MST 2014
Thank you for the reply..

i have moved the setting of address to the point when i am handling the SETUP request. Also i noticed that i must clear the SETUP bit in DEVCMDSTAT before i set the new address. Previously, i clear the SETUP bit very late at the last step just before i left the SETUP request ISR..now i am clearing the SETUP bit the moment i enter into the SETUP request ISR...

Anyway, now i can write a new address into my LPC11U37.. but now the host reseting my device back to address 0 after the set address request and a get device descriptor request. During debugging, i put a breakpoint at get device descriptor and each time i stop at the breakpoint, my device address will switch between 0 and the new address.

i am guessing some thing went wrong in the get descriptor step after the new address and the host resets my device back to address 0. I learnt this from another post i found on the internet...
http://libusb.6.n5.nabble.com/USB-bus-reset-td5521893.html

i am guessing its related to some problems in the descriptors... or some problems in the EPSKIP... see my previous post on EPSKIP registers
http://www.lpcware.com/content/forum/lpc11u37-usb-device-register-endpoint-skip

Thank you.

[lpcware]

Content originally posted in LPCWare by Tsuneo on Thu Dec 11 02:01:13 MST 2014

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Quote:
2. i am writing the new address into DEVCMDSTAT register inside the ISR of the endpoint0 IN interrupt (which correspond to the STATUS stage completion).

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When your firmware sees the completion ISR on the IN EP0, the STATUS stage has finished on the bus.  I know you are faithful to the USB2.0 spec, 9.2.6.3 Set Address Processing ;-)
But the user manual of this MCU states as follows,

11.6.1 USB Device Command/Status register (DEVCMDSTAT)
DEV_ADDR
When receiving a SetAddress Control Request from the USB host, software must program the new address before completing the status phase of the SetAddress Control Request.

Your firmware has to write to DEV_ADDR, when it sees SETUP stage of Set_Address request.

The process of Set_Address depends on SIE design so much. To implement your own stack, always refer to the MCU manual, if it would require specific sequence or not.

Tsuneo