The PIC32MZ triggers are used to initiate and control all of the DMA transfers in the OpenScope MZ. When a trigger is enabled, a data acquisition will run
continuously before the trigger event because it is not known when the trigger event will occur. Data acquisition will also continue to run until all post trigger data is
collected. Due to data acquisition size limitations, it is not possible to measure a point of interest that exists too far in advance prior to the trigger event. The reverse
for a point of interest too far after a trigger event is also true.
Supported triggers for the oscilloscope are:
Rising or Falling Edge triggers
Rise/Fall time with lower and upper threshold
By default WaveForms Live sets the lower threshold 30 mV below the upper threshold
Supported triggers for the logic analyzer are:
Rising, Falling or either Edge triggers
Any of the 10 LA signal channels in any combination
Pattern matching of the LA signal channels is not supported
8 out of 8 DMA channels available on the PIC32MZ are used on the OpenScope MZ. Two channels are dedicated to UART, a pair of DMA channels are assigned
to each interleaved ADC () channel for a total of four channels, one channel is shared between the function generator and the logic analyzer and one dedicated to
hardware protocol communication. All DMA channels can be triggered on any interrupt event and do not require the use of an ISR.
DMA is used to transfer data without utilizing the CPU by working in parallel with the CPU and has to ability to access peripherals and non-cached memory at much
greater speeds. DMA cell transfers are serialized so care is taken in the OpenScope firmware to ensure that multiple channels are not triggered above 10 MT/s to
prevent a high priority channel from stalling all other DMA channels.
9 PWM channels of the PIC32MZ are implemented on the OpenScope MZ. Two are used in the interleaving of the ADC () channels, three are used for offsets for
the AWG and both analog input channels, two are used for the DC outputs, and the remaining two used as offsets for the DC outputs.
The PWM outputs have 330 unique values ranging from 0 V to 3.3 V, with a step size of 10 mV. The internal clock runs at 100 MHz (), providing a PWM frequency
of 303 kHz (). All of the analog designs on the OpenScope MZ are based on PWM values from 50 to 300 to allow some headroom for calibration.
The LEDs on the OpenScope MZ are used to indicate the current status of the OpenScope MZ hardware as follows:
Note: Firmware versions prior to 1.2.0 will not exhibit the LED () behavior described below.
Blue Off - Device is booting and not ready to use.
Blue Flashing - Device is booted and ready to use but Wifi is not connected.
Blue Solid - Device is booted and ready to use and Wifi is connected.
The three other LEDs blink the last octet of the OpenScope MZ's IP Address.
Red Solid - Calibration or acquisition in progress.
All user LEDs Solid - An error has occurred. Reboot the OpenScope MZ.
When connected to a Wifi network the 3 user LEDs display the last octet of the OpenScope MZ's IP address by blinking the number of times corresponding
to that digit of the last octet in decimal. For example an OpenScope MZ with an IP address ending in '123' would blink LD1 once, LD2 twice and LD3 three
times.
DMA
PWM
Troubleshooting
LED Indicators
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