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In uart terms this is a long period of zeros, last time I messed with windows, it very poorly handled breaks at the driver level, tools like hyperterm, etc you have to restart, plus any software I wrote, one would hope they would have fixed this buy now but uart is so low priority and even then com ports were going away, so why would they bother to fix it? See how your software handles this. NO absolutely not, different hardware and different computers can definitely affect the results/success. You seem to be asking about a software product and not necessarily hardware, but you asked if the physical layer works in the same way. The 8x or 16x oversampling helps with finding the middle of a bit cell, but one has to assume it is reset on the edge of the start bit so you have to make it through 10 give or take bit cells with the worst error both side has chosen. So your two sides are not communicating at the same speed. This is assuming a perfect clock but if the mcu is using an internal R/C oscillator, then that clock has more error than a crystal reference and it can/will drift with temperature. 16x oversampling and it gets worse.īottom line is sometimes the variation is small and sometimes not as small. So 8000000/833 = 9603 which may not seem like much but often these are often divided down say 8x and you want to run your mcu at the lowest clock you can to save power. On the ideal reference clock side you are creating an approximation, say 8MHz/9600 = 833.333. Some hardware will use the proper crystal/reference, within a tolerance of course, to generate these speeds, but often, specifically on the uC side for sure, you are not doing that. While you may set the baud rate for a specific speed 9600 for example, the reality is you are rarely at that speed. Those would be the minimum tests on voltage levels, you can do more there. So for example some random uart to RS232C product may land anywhere within that, if you are testing your hardware product you probably want to test those limits the low end to see if the product functions and the high end (+/- 15V) does not damage the product. RS232C has a defined range for what a "1" and what a "0" is. The protocol does not really have a name UART protocol is probably the closest, but there are variations on a theme there.īut this brings up the question does your product rely on RS232 levels or "TTL" levels (as in 5V, or 3.3V or 1.8V or other).
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Are you interested in testing the hardware or testing your software product? This is a hardware site.Īs pointed out in comments RS232 is not a protocol standard it is a pinout/voltage level standard.