lpcware

Setting Endpoint maxpacketsize for LPC11U37H

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by siangming on Thu Dec 11 19:11:09 MST 2014
Hi all,

I have a few questions for implementing USB on LPC11U37H and for USB in general..
Please bear with me..

1. Can i configure the LPC11U37H as a low-speed usb device instead of full-speed?
Firmware-wise, i have to configure the descriptors as per low-speed specs (example: Endpoint max packet size, etc...)
Hardware-wise, i have to put a pull-up resistor to the D- signal line. How about the USB clock?



2. On the topic of endpoint packet size... In the LPC11U37H, if i were to use it as full-speed, how do i configure the chip to set the endpoint max packet size? for example, in full-speed, the default control endpoint can have a maximum packet size of 8, 16, 32 or 64. (according to Jan Axelson, USB COMPLETE, fourth editon, chapter 3 page 68).
For LPC11U37, it is also stated in the manual (page 221, table 211) that "The packet size is configurable up to the maximum value shown in Table 211 for each type of end point."

Does it mean that the LPC11U37H can perform at various setting of different max packet size?

If so, do i have to specify to the chip to use which packet size setting?

if not, what max packet size will the chip use in the example of a full-speed control endpoint? And how will the chip know to limit its control endpoint max packet size to 8 in low-speed mode?



3. On the host side, i know we specify the endpoints max packet size in the descriptors (control EP packet size in device descriptor, other EP packet size in their respective endpoint descriptors). So these max packets sizes in the descriptors must tally with the settings in question 2 above?

Thank you so much for your patience...

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