I am using CW lite to test voltage glitching on an STM32G0 microcontroller. I’ve set up a really basic test circuit with 10 ohms shunt resistor, and the CW connected to the board via a coaxial cable. Currently I am able to glitch the target somewhat successfully, but I’d like to ask a few questions.
The picture below shows a capture of a glitch without the target being in the circuit. The glitch shape is fairly distinct.
The second image show the same glitch issued when the target is in place. No external components are added to the circuit:
Now the crowbar circuit cannot pull the rail to ground; that only happens at the end of the glitch. The MCU gets reset though. Here are my scope settings:
cwlite Device fw_version = major = 0 minor = 50 debug = 0 gain = mode = high gain = 30 db = 24.8359375 adc = state = True basic_mode = rising_edge timeout = 2 offset = 0 presamples = 0 samples = 5000 decimate = 1 trig_count = 1040748980 fifo_fill_mode = normal clock = adc_src = clkgen_x1 adc_phase = 0 adc_freq = 99999996 adc_rate = 99999996.0 adc_locked = True freq_ctr = 0 freq_ctr_src = extclk clkgen_src = system extclk_freq = 10000000 clkgen_mul = 25 clkgen_div = 24 clkgen_freq = 100000000.0 clkgen_locked = True trigger = triggers = nrst module = basic io = tio1 = serial_rx tio2 = serial_tx tio3 = high_z tio4 = high_z pdid = high_z pdic = high_z nrst = high_z glitch_hp = True glitch_lp = False extclk_src = hs1 hs2 = clkgen target_pwr = True tio_states = (0, 0, 1, 0) cdc_settings = bytearray(b'\x00\x00\x00\x00') glitch = clk_src = clkgen width = 48.828125 width_fine = 0 offset = 10.15625 offset_fine = 0 trigger_src = manual arm_timing = after_scope ext_offset = 101 repeat = 100 output = enable_only
I’d like to know what could be causing that behavior, and if there’s a way for rectifying it. I will also use the topic for asking a few other things:
- What is the difference between glitch_hp and glitch_lp, and more importantly, what factors should we concider when selecting one or the orher?
- Can they be used simultaneously?