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11 years ago.
LPC1768 IF+ & IF- IF+/-
On the LPC1768 where do pins 37/38 marked IF+ and IF- connect to, and what is there function. On the schematic PDF ( http://mbed.org/media/uploads/chris/mbed-005.1.pdf ) I see on page 1 pins 10 and 11 on IC1 are labled IF_D+ and IF_D- and these are wired to pins 37 / 38 on the module. (see page 5).
Looking at the NXP Semiconductors LPC1769/68/67/66/65/64/63 manual,
pin 10
Quote:
VDDA analog 3.3 V pad supply voltage: This should be nominally the same voltage as VDD(3V3) but should be isolated to minimize noise and error. This voltage is used to power the ADC and DAC. This pin should be tied to 3.3 V if the ADC and DAC are not used.
and for pin 11
Quote:
VSSA analog ground: 0 V reference. This should nominally be the same voltage as VSS, but should be isolated to minimize noise and error.
can someone confirm this please?
Yours Simon M.
1 Answer
11 years ago.
The IF+ en IF- pins go to the interface chip (or magic chip) that provides your host USB link for downloading and PC serial coms. It does not connect directly to the target lpc1768 (so pin 10, pin 11 descriptions from your quote are not related to IF+ & IF-).
I believe originally it was intended to provide a separate USB host connection when the mbed is plugged into some motherboard and the USB mini connector is not that optimal to use. However, in practice it doesnt seem very useful due to issues regarding powersupply etc. Recommend not to use it.