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We have a product that we have had developed for some time and we are experiencing a problem where the sleep time is lengthening beyond the 1s setting at low temperature and in some cases does not appear to come out of sleep. We are using an ext 32Khz oscillator. I am trying to identify the source of the problem. Switching to the internal oscillator seems to fix the issue but this is inaccurate. What would affect extermnal oscillator issues with the PSOC1. Oh yeah, we have practically every block (both digital and analog) powered down to conserve power.
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PSoC 1
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I failed to mention that the part number is the CY8C27243
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"Low temperature" may induce high humidity which could affect the circuitry (caps) for the x-tal. Try to confirm that the error persist when cooling is made in the absense of moisture (zeolith, silica gel).
Bob
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These may help -
www.cypress.com/?docID=32328
www.cypress.com/?docID=33272
Former includes IMO Startup issues.
Regards, Dana.
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The problem you have mentioned seems to be the -R problem. I suggest you to try changing the ECO_TR register setting to Medium HIGH or the HIGHEST amplitude mode (refer to AN2027 for register setting). This will increase -R of the device and will ensure that device does start properly.
Best regards,
Pushek
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Xtal oscillators are “tricky” to troubleshoot, impedance measurements of Xtal parameters
difficult because of range of Z’s, probes to look at oscillator running have to be ultra
low C as you are dealing with very low oscillator C values to start with. To overcome this
problem use scopes with high sensitivity, and decouple probe from Osc nodes via Hi series
R or low C values to minimally affect Osc.
Xtal oscillators typically operate at very hi Z resonant produced values, easily affected
by anything that “touches” them.
Google “crystal oscillator basic application note”, lots of ap notes.
Pay particular attention to the fact that external Xtal C ratios provide voltage gain in
the effective transfer function of the Xtal and the 2 caps.
Regards, Dana.