It seems even things barely worth faking are being faked also. I have a bag of 500 74HC595 shift registers, that are actually rebadged 74HC596s (as in, open collector, SINK, not SOURCE-capable).
Which are useless for my application :-( On Fri, 25 Jan 2019 at 20:58, Bill van Dijk <[email protected]> wrote: > There can be a few different reasons for the i2c buss to hang, and may not > be the fault of the DS3231. For instance, if there is a software interrupt > during an i2c read or write, that can do it. Are you using a mpu based > hardware i2c engine, or do you bit-bang the buss? > > > > If the DS3231 is battery backed up, than resetting the power will not > reset the buss either. In cases where I use a battery backup, I use a small > routine to test the buss at every startup, including brownout and watch dog > events: > > > > void I2C_Test() //test to see if I2C line is in a valid (stopped) state > > { > > if //test I2C line > > (!input(i2c_SDA)) //if SDA stuck low - Fault Condition > > { > > I2CEN=0; //temporary disable I2C Hardware Module > > output_drive(i2c_SCL); //set SCL as output > > while > > (!input(i2c_SDA)) //Continue loop until SDA is released (high) > > { > > output_toggle(i2c_SCL); //Toggle I2C clock line till fault clears > > delay_us(10); > > } > > output_float(i2c_SCL); // set SCL back as input > > I2CEN=1; // re-enable I2C Hardware Module > > } > > } > > > > Bill > > > > > > > > *From:* [email protected] [mailto:[email protected]] *On > Behalf Of *Luka C > *Sent:* Friday, January 25, 2019 3:45 PM > *To:* neonixie-l <[email protected]> > *Subject:* Re: [neonixie-l] Re: Counterfeit RTC modules > > > > I have written previously about a similar incident with ATmega328p chips > ordered from Aliexpress. They did not arrived in a reel, but just packed in > a small plastic bag. Two of them worked fine, but Atmel Studio was unable > to even read the ID of the third one, thus rendering it unprogrammable and > useless..and since it's an SMD, it was not as easy as just popping it out > of the socket. I guess they are chips which failed QC and somehow, these > companies got them, performed a somewhat "basic check" and sold them as new > ones. > > > > I have also ordered a lot of 10 DS3231 chips from some other Aliexpress > seller (they had considerable 5* ratings so I decided to give it a try). > They were like 14$/10pcs. The chips worked, the time is still very precise > after two years of operation of the older clock I made. However, I did > notice one "bug" in the chip. If you keep querying the chip too often (like > in an unconditional loop) for seconds, it will eventually hang the I2C > line. The solution was to set a timeout for I2C read operation, and if > timeout does occur, the master (microcontroller) has to keep clocking the > SCL line until the DS3231 releases the bus. However, I've read some people > reporting the same "bug" on multiple sites, so I'm not sure if it's a "bug" > specific to possibly counterfeit chips or just a general bug that affects > genuine ones as well. > > > On Thursday, January 3, 2019 at 1:41:52 AM UTC+1, gregebert wrote: > > For now I'm going to hold off on any experiments that require > code-changes. I'll keep this RTC chip online for additional experiments; > known-good RTC will go into the second board-set. > > It appears the alarm registers are testable with software; I dont have the > INT/SQW pin connected in my system. > > > > I'm really itching to get the NIMO lit-up and running. So close to > actually firing it up, but I wont attempt that unless everything is 100% > stable. Mindset is that I have only 1 chance to get it right and it must be > right the first time. Anything that can go wrong and remain uncorrected for > more than a few milliseconds is assumed to result in a dead NIMO tube, and > I only have 1. > > > > > > -- > You received this message because you are subscribed to the Google Groups > "neonixie-l" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > To view this discussion on the web, visit > https://groups.google.com/d/msgid/neonixie-l/9529a437-2084-41b9-af82-158aa95ff505%40googlegroups.com > <https://groups.google.com/d/msgid/neonixie-l/9529a437-2084-41b9-af82-158aa95ff505%40googlegroups.com?utm_medium=email&utm_source=footer> > . > For more options, visit https://groups.google.com/d/optout. > > -- > You received this message because you are subscribed to the Google Groups > "neonixie-l" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > To view this discussion on the web, visit > https://groups.google.com/d/msgid/neonixie-l/003a01d4b4f0%24aaac8250%24000586f0%24%40gmail.com > <https://groups.google.com/d/msgid/neonixie-l/003a01d4b4f0%24aaac8250%24000586f0%24%40gmail.com?utm_medium=email&utm_source=footer> > . > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. 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