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Updated LPC43xx USB DFU Notes (markdown)

mossmann
2012-10-13 08:43:26 -07:00
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LPC43xx-USB-DFU-Notes.md

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# LPC43xx USB DFU Notes
The LPC4350/40/30/20 contain USB DFU bootloader support in their ROM. By selecting the appropriate boot mode (either USB0 or USB1), the device will come up on USB at power-up or reset, and implement the popular and well-documented [USB DFU protocol](http://www.usb.org/developers/devclass_docs/DFU_1.1.pdf).
It appears that the LPC43xx boot ROM will identify the available clock sources and frequencies, to some extent. Unfortunately, the current Jellybean prototype does not offer any high-precision clock source on-board, and the Si5351C (on Lemondrop) does not produce any clock signals by default. So we may not be able to use the USB DFU bootloader until we provide a accurate clock source at power-up. It's possible adding a 32.768KHz watch crystal would provide this without much additional BOM cost?
The April 16, 2012 Jellybean design has a voltage divider for VBUS that is fed to the LPC43xx to detect that a USB host is present. Measuring the divided voltage, the USB0_VBUS only reaches 0.4V, which fails to trip the USB bootloader code. It looks like NXP's intent is to directly connect VBUS to the USB0_VBUS. Indeed, when I shorted R10 with tweezers, the USB bootloader sprung into action. I would recommend changing R10 to 0 Ohms and R11 to DNP, or removing R10 and R11 altogether.
The LPC43xx contains USB DFU bootloader support in ROM. By selecting the appropriate boot mode (USB0), the device will come up on USB at power-up or reset, and implement the popular and well-documented [USB DFU protocol](http://www.usb.org/developers/devclass_docs/DFU_1.1.pdf).
## Setup
### Boot Mode Jumpers
Set the boot mode jumpers to USB0: BOOT[0:3] = "1010". Jumper setting takes effect at the next power-on or reset. (I'll probably rig up a reset button to P2 "LPC_JTAG" or P14 "LPC_ISP".)
Set the boot mode jumpers to USB0: BOOT[0:3] = "1010". Jumper setting takes effect at the next power-on or reset. (You can rig up a reset button to P2 "LPC_JTAG" or P14 "LPC_ISP".)
### USB DFU Utility
http://dfu-util.gnumonks.org/
You need the latest source from git for some reason.
## Usage Notes
DFU boot downloads to RAM then executes. Need a DFU suffix, but also a header
@@ -40,3 +36,10 @@ Check for device:
Download (I used the latest dfu-util from git)
> /usr/local/bin/dfu-util -d 1fc9:000c -a 0 -D load.dfu
Also make sure that the binary is linked for execution at address 0x00000000. This is the default for our linker scripts.
# Jellybean Notes
A 12 MHz clock signal must be supplied to the LPC4330 at boot time.
The April 16, 2012 Jellybean design has a voltage divider for VBUS that is fed to the LPC43xx to detect that a USB host is present. Measuring the divided voltage, the USB0_VBUS only reaches 0.4V, which fails to trip the USB bootloader code. It looks like NXP's intent is to directly connect VBUS to the USB0_VBUS. Indeed, when I shorted R10 with tweezers, the USB bootloader sprung into action. I would recommend changing R10 to 0 Ohms and R11 to DNP, or removing R10 and R11 altogether.