Update user manual
Document scripts puzzle-passwd and puzzle-ntpcfg. Document command REALTIME?.
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@ -211,7 +211,20 @@ to open the USB serial port of the Red Pitaya.
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Set the baud rate to 115200 bps, character format to `8N1`.
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Press Enter to get a login prompt on the console.
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Use login `root` with password `root`.
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Login as user `root`.
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The default password is `root`.
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### Changing the password
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The default login password is `root`, but this can be changed.
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To change the password, login on the console and run the command `puzzle-passwd`.
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The tool will prompt to type a new root password.
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The changed password will be persistently stored on the SD card.
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Do not use the normal Unix command `passwd`.
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This tool does not write the new password to the SD card; therefore the changes will be forgotten after reboot.
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## Network access
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@ -241,16 +254,47 @@ This is the same host name as used by the official Red Pitaya software.
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It is possible to run an SSH server on the Red Pitaya.
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This can be used to remotely log in on the Linux system.
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To login via SSH, use username `root` with password `root`.
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To login via SSH, use username `root` and the same password used for logging in via the USB console.
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For security reasons, the SSH server is disabled by default.
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The default password is `root`.
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It is recommended to change the password before enabling SSH access.
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An SSH server with an easy-to-guess password should never be connected to an untrusted network.
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If you want to use the SSH server, you have to enable it explicitly.
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To enable the SSH server, login on the USB console as described above.
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Then run the following command: `puzzle-sshcfg enable` .
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Finally, run `reboot` to reboot the Red Pitaya.
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For security reasons, the SSH server is disabled by default.
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If you want to login via SSH, it must be enabled explicitly.
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Use the following steps to enable the SSH server:
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- Login on the USB console as described above.
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- Set a safe password by running command: `puzzle-passwd`
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- Enable the SSH server by running command: `puzzle-sshcfg enable`
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- Reboot the Red Pitaya by running command: `reboot`
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From this point onward, the SSH server will be started automatically during boot.
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You can again use the command `puzzle-sshcfg` to disable SSH access.
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### NTP configuration
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Optionally, an NTP server may be configured to synchronize the system clock via the network.
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Without an NTP server, the system clock of the Red Pitaya is initialized to the year 1970 on power-on.
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The only feature that uses the system clock is the remote control command `REALTIME?` .
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If this command is used, configuring an NTP server is necessary to get correct results.
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If this command is not used, synchronizing the system clock is not important.
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To configure an NTP server, use the following steps:
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- Login on the Red Pitaya via USB console or SSH as described above.
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- Run the command `puzzle-ntpcfg server <IP-address>` .
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This command configures Chrony to synchronize to the specified NTP server.
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The configuration is also written to the SD card and used during boot.
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Optionally, a poll interval can be specified as a power of 2 in seconds.
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For example: `puzzle-ntpcfg server <IP-address> poll 5` specifies a poll interval of 32 seconds.
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Sub-millisecond accuracy can be achieved with an NTP server in the local network and `poll 0` (poll each second).
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Poll intervals shorter than 64 seconds must only be used with a dedicated NTP server in the local network.
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Using such short poll intervals with a public NTP server is considered abuse.
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## Data stream protocol
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@ -330,6 +374,7 @@ In the response string, such data elements are separated by space characters.
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| `*IDN?` | Instrument identification. |
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| `RESET` | Restore default settings. |
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| `TIMESTAMP?` | Timestamp counter. |
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| `REALTIME?` | System time and timestamp counter. |
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| `AIN:CHANNELS:COUNT?` | Number of input channels. |
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| `AIN:CHANNELS:ACTIVE` | Number of active input channels. |
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| `AIN:CHn:RANGE` | Analog input range. |
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@ -391,6 +436,23 @@ Any ongoing analog acquisition is stopped.
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Query: `TIMESTAMP?` <br>
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Response: decimal integer, representing the current timestamp in units of 8 ns.
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### `REALTIME?`
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Query: `REALTIME?` <br>
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Response: system time and firmware timestamp, separated by a space character.
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The system time is represented as a floating point number denoting the number of seconds since 1970-01-01 00:00 UTC (ignoring leap seconds).
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The firmware timestamp is represented as a decimal integer denoting the current timestamp in units of 8 ns.
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This command is only useful if the Red Pitaya is configured to synchronize its system clock via NTP.
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Without NTP, the system time of the Red Pitaya will be incorrect and essentially meaningless.
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The system time and firmware timestamp are captured nearly simultaneous, but not exactly simultaneous.
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The mismatch between these two time values is almost always less than 10 microseconds.
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The overall accuracy of the system time is limited by the synchronization via NTP.
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In practice, sub-millisecond accuracy is possible with an NTP server in the local network.
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### `AIN:CHANNELS:COUNT?`
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Query: `AIN:CHANNELS:COUNT?` <br>
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