Hello, how can I make the waveform show its data in hex or bin? I keep getting waveforms without this information. Please help.
Did you setup a analyzer for the protocol from the right side tab? that line over the waveform is where the analyzers display the decoded data
yes, D0 is CAN[1]. D1 is CAN… as shown in pic…
OK, here is a clearer pic… why does it show error? i use a traditional scope it display the same waveform… anyone can help?
@ruskurt what exactly are you connecting to? Your earlier post was showing I2C, but now showing CAN protocol? Also, your labels are “Master Tx” and “Slave Tx” which aren’t typical for CAN, as the CAN bus is peer-to-peer not a master/slave type protocol.
See: CAN bus - Wikipedia
My guess is that you either have the wrong protocol decoder selected, or possibly the wrong bit-rate/settings being used.
eralier pic is from Logic2 website, Master Tx is he CAN node that’s requesting to tx, Slave Tx is the receiver end…
Are you connecting to CAN bus, or a CAN IC? If a chip, then what IC/pins?
CAN transceiver: MCP2551
According to MCP2551 datasheet, the IC pinout is:
1 TXD: Transmit Data Input
2 VSS: Ground
3 VDD: Supply Voltage
4 RXD: Receive Data Output
5 VREF: Reference Output Voltage
6 CANL: CAN Low-Level Voltage I/O
7 CANH: CAN High-Level Voltage I/O
8 RS: Slope-Control Input
Which pins are you connecting to Logic?
Do you have newer Logic w/ analog?
What are voltages on pin 3 (VDD) and pin 8 (RS)?
Is RS pin (8) > 0.4 VDD (i.e., not in standby)?
Note: pin 4 (RXD) should be best pin to observe bus, and match pattern of pin 6 (CANL).
See Controller Area Network at: Decode Differential and High Voltage Data | Saleae Support
i m probing at Tx pin1 on both transceivers it seems correct when i observed at the traditional scope and i m able to control the peripheral at slave mcu…
What are the CAN analyzer settings?
Note: Bit Rate (Bits/s) is typically 500 kbps (i.e., 500000 Bits/s), or 2 us/bit
Also, probing the RXD (4) pin of any ‘active’ node on the bus should show same data, while TXD (1) only shows transmission bits, not all the bits on the ‘bus’ – so you may have some decoding problems (ACK errors, as ACK is transmitted by receiving node(s) on bus, not the transmitter).
Suggestions:
- Add a channel to RXD(4) of either node
- Set bit rate to 500000 on CAN analyzer
bitrate: 50000, can’t use 500k cause it says sampling error…
What is the sample rate (from device capture settings) on the channel?
Note: If the CAN bus is running at 500 kbps, then setting the decoder to 50 kbps just won’t work 
(i.e., you must set the bit rate to match the CAN bus settings)
What Saleae Logic do you have?
See: How to Identify Each Saleae Device | Saleae Support to help identify
MCU CAN bus is set at 500kbps, on Salese i just can’t place it to 500k , it show “sampling error… reduce sampling rate”
Check the support link about sample rates:
… as well as:
I know the cheap clones have sample rate issues, but you should be able to sample at >500 kS/s with any genuine logic hardware on at least a USB 2.0 port.
@ruskurt can you reply/attach a sample capture file (*.sal) that fails to decode?
Looking at your screenshot:
… it sure looks like 2 us/bit pulses were captured (as dt between +0.5 ms and +0.6 ms grid lines is a 100 us interval, and the shortest pulses look about ~1/50th of the width).
So, wondering if you might be having other issues (tiny glitches or ??)
i dun not think there is any gitch, as i m able to control the slave CAN via Stepper motor drivers.
i enclosed another screenshot of CAN using Analog Device2, look, the waveform is same and able to display hex info…albeit same bullshit to reduce bit rate, i set AD2 bitrate to 500kbps
It looks like it decodes okay at 500 kS/s, so that is likely what you need to use. If you can attach the capture file (*.sal), maybe can provide better feedback as the screenshots don’t provide enough detail.
ok, how to obtain the *.sa file?