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from instruments import *
from matplotlib import pyplot as plt
from IPython.display import display, clear_output
import numpy as np
import math
import time
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# STM32F417ZET6 revision 4 bootloader not working when crystal caps are 27pF, works intermittenly with 15pF.
# Another board with STM32F417ZET6 revision 2 works reliably with 27 pF caps.
# Crystal frequency 7.999988 MHz on not working board with the 27 pF caps.
# Freqs on working boards: 7.999937 MHz, 7.999965 MHz
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scope.screenshot() # Not working board, crystal startup in normal application, blue = VDD, yellow = Xout/PH1
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scope.screenshot() # Working board, crystal startup in normal application
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scope.screenshot() # Working board, crystal startup in bootloader
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scope.screenshot() # Not working board, crystal startup in bootloader
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# Working STM32F417 has bootloader revision 9.1
# Not working one has 3.1
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scope.screenshot() # Crystal startup time with 20 pF caps
# Yellow = Xout, Blue = GPIO pin raised with HSEON and cleared when HSERDY
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scope.screenshot() # Crystal startup time with 15 pF caps
# Yellow = Xout, Blue = GPIO pin raised with HSEON and cleared when HSERDY
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# Conclusion: V3.1 bootloader has needlessly short timeout for crystal startup.
# The larger capacitors push the startup time beyond the limit.