thanhtran 10 Posted November 26, 2012 Share Posted November 26, 2012 Can we power the MSP430F5510 from USB without needing an external LDO regulator to provide 3.3v on the Vcc? Here is what I see: 1. If I plug the MSP430F5510 to a USB port, and without any power is applied to the MSP430 VCC pins, I see the pin VUSB provides a 3.3v. This is said as LDO output on the datasheet. 2. If I have 3.3v from an external power source to power the MSP430 then the chip would come alive and enumeration happens. So naturally I think I should be able to connect the VUSB to the VCC pin and should have the MSP430 powered by this VUSB power. 3. But when I do this, the MSP430 is not coming up and not doing enumeration. 4. If I have a LDO connecting to the 5v VBUS to create 3.3v and connect this 3.3v to Vcc, it works fine. So, is there a way we can use the built-in LDO? Thanks -Thanh Quote Link to post Share on other sites
RobG 1,892 Posted November 27, 2012 Share Posted November 27, 2012 You can use it but the maximum current you can draw from VUSB is 12mA. thanhtran 1 Quote Link to post Share on other sites
thanhtran 10 Posted November 27, 2012 Author Share Posted November 27, 2012 Hi Rob, thanks for the response. 12mA is more than what I need, especially for an MSP.with couple sensors. Currently I don't have any extra load, just the MSP430 alone (kind of like your 5510 development board). But it doesn't seem to come alive in this mode. I have no idea why. Do I need to set something in the software? I was running your USB-UART code. Thanks -Thanh Quote Link to post Share on other sites
RobG 1,892 Posted November 27, 2012 Share Posted November 27, 2012 It should work even when you exceed the limit a bit, see below, 5110 powered by VUSB. bluehash 1 Quote Link to post Share on other sites
jazz 209 Posted November 27, 2012 Share Posted November 27, 2012 Hi Rob, thanks for the response. 12mA is more than what I need, especially for an MSP.with couple sensors. Currently I don't have any extra load, just the MSP430 alone (kind of like your 5510 development board). But it doesn't seem to come alive in this mode. I have no idea why. Do I need to set something in the software? I was running your USB-UART code. When MSP430F5510 is plugged to USB port LDO is enabled by default (3.3V on VUSB). It is not related to firmware. I use it (LDO) during development of non-USB software without any problem. Plug MSP430F5510 to USB and try blinking led example (flashed by USB BSL) without external supply. Quote Link to post Share on other sites
thanhtran 10 Posted November 28, 2012 Author Share Posted November 28, 2012 Thanks Jazz and Rob for the replies. I connected the VUSB to the MSP VCC. I tried a code that flashed some LEDs. It worked. But If I loaded some code that supposed to enumerate the USB port, the USB port itself didn't enumerate. I looked at Rob's circuit (http://forum.43oh.com/index.php?app=core&module=attach§ion=attach&attach_rel_module=post&attach_id=2190) and realized that I didn't have a diode between VUSB and the MSP VCC line. After adding this diode, the USB is now enumerate just fine. Not sure why, but I will use this Thanks again -Thanh Quote Link to post Share on other sites
thanhtran 10 Posted November 28, 2012 Author Share Posted November 28, 2012 My 5510 test board next to a SD card vicvelcro and jazz 2 Quote Link to post Share on other sites
spirilis 1,265 Posted November 28, 2012 Share Posted November 28, 2012 Toner transfer? Nice tin finish! Sent from my C3PO via Tapatalk Quote Link to post Share on other sites
thanhtran 10 Posted November 28, 2012 Author Share Posted November 28, 2012 Yes, I use toner transfer method for this board. It gives correct track sizes compared UV transfer method that I used to use. Thanks. Btw, we are neighbor. I'm in Fredrick. Quote Link to post Share on other sites
jazz 209 Posted December 1, 2012 Share Posted December 1, 2012 I connected the VUSB to the MSP VCC. I tried a code that flashed some LEDs. It worked. But If I loaded some code that supposed to enumerate the USB port, the USB port itself didn't enumerate. I looked at Rob's circuit (http://forum.43oh.com/index.php?app=core&module=attach§ion=attach&attach_rel_module=post&attach_id=2190) and realized that I didn't have a diode between VUSB and the MSP VCC line. After adding this diode, the USB is now enumerate just fine. Not sure why, but I will use this Glad to see that someone is making own version of MSP430F5510 board. It is good that is working now, but I am not sure that problem was in VUSB/VCC diode. My board don't have VUSB/VCC diode and it is working with flashing LED example and enumerate with original TI USB stack. Problem is probably somewhere else (on board), but if it is working and chip is cold all the time, don't worry. Quote Link to post Share on other sites
silentburner 1 Posted November 21, 2013 Share Posted November 21, 2013 Solved the Problem. On long USB-Lines, MSP needs more Power to drive the Line (pulses of 25mA and higher). Just add more Capacitors (10uF) to VBUS AND especially to VUSB (10uF). The nessesary power will be sourced by the bigger caps then. vicvelcro 1 Quote Link to post Share on other sites
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