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MSP430F5529: Crystal required for USB operation

Danilo A.
Mastermind 32735 points

Part Number: MSP430F5529

Hi Team,

We received the following inquiries from our customer.

I would like to use the MSP430F5529 in an application to test different voltage rails via pogo pins. I will be utilizing the Vref for analog reference and analog switches to input into the 3 of ADC input pins. My application should output data to the serial console over USB. My questions are as follows. 

1. I understand the MSP430 has USB built in so I can directly connect the USB 2.0 signals to the MCU (with proper ESD protection). Do I need any other components to enable USB operation such as an external clock. I understand there is an integrated clock in the MSP but would this application benefit from and external clock? Will an external clock/crystal reduce current drawn from the MSP? From the eval board schematic, I see there are two external crystals being used, which makes me question if it a requirement in this application.

2. Do I need to configure the MSP to boot with USB. If plug the USB signals to MSP will it appear as a COM device and ready to be programmed? I understand the BSL is preprogrammed on the device, but the datasheet also mentioned is it protected by a user defined password as well? Can you explain further on how I can get around the password and program the board with my code. 

3. In the datasheet section 8.3, footnote 2 suggested the DVCC and AVCC should be from the same source. My current design has the analog and digital supplies (3.3V) from different supply components so the analog circuity is not susceptible to noise or spikes. Will that suffice? Should I opt into keeping the supplies the same and utilize a pi filter for the core and analog inputs.

Regards,

Danilo

  • 0
    TI__Guru 56685 points

    Hello Danilo,

    1. Yes an external HF crystal is required for USB operation. Please see the MSP430 USB Development Package and particularly this app note: Starting a USB Design

    with MSP430. for other requirements. 

    2. USB BSL is provided by default. You must invoke the BSL when applying power by pulling the PR pin high as the device is powering up. On the device is a very basic version of USB Stack with limited BSL commands. This mini stack is used to download onto the device the RAM_USB_BSL which contains full USB stack and BSL command set. Please see the following app note and the PYTHON GUI located in the USB Development Package for details. : USB Field Firmware Update with MSP430

    3. They key here is the AVCC and DVCC pins must rise and fall at the same time during power up and power down. Typically, customers will place and inductor or ferrite bead between AVCC and DVCC lines if keeping them seperate to ensure this. However, most customers just tie everything to DVCC. 

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