Part Number:MSP430F5528
Greetings,
I'm designing a space-constrained board with the intention of using the MSP430F5528-IRGC. For the scope of the project, the MSP430F55xx is intended to emulate a MSC device to store configuration data from a (Windows) PC. After it disconnects from the USB port, its use from there is just to initialize an embedded system every time it's power-cycle'd and do nothing else (sleep?). To reduce footprint, I'm planning to use only the USB BSL to do production programming. Also if it helps, the current objectives are fast start-up time and 400kHz I2C master.
1. So upon using a fresh un-programmed chip, would it be possible to use an external oscillator leaving the XT1-output and XT2-output floating and feeding the external oscillators output into XT1-input and XT2-input? This is without touching the XT bypass settings.
2. Could I use just XT2 only, while leaving XT1 pins floating? I've read somewhere that XT1 is required but there's also a post here (MSP430G2xxx series I believe) that said that the microcontroller defaults to DCO if it can't detect XT1 on startup.
The current external oscillators I've been eyeing are the SiTime 1552 series (for XT1 if needed; 180-300ms startup time) and SiTime 1618 series for XT2 at 12MHz or 24MHz. Their "drive strength" seems to be configurable.
For the 1552 series, I saw this diagram illustrating their "nanodrive" function":
https://www.sitime.com/sites/default/files/gated/AN10037-SiT15xx-Optimized-Settings-for-32kHz-Inputs-MCUs.pdf
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As for the XT2 (12/24 MHz) oscillator, I'm thinking I need to match its "drive strength" configuration to the MSP430F55xx microcontroller. I'm also thinking of looking for a 4MHz oscillator (or crystal) just in case there's too much of a hassle to wrestle with 12/24MHz.
Thanks for any help,
Scott