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Article archives

PackMan in practice

Posted by Jeffrey Lee on 09:00, 14/9/2018 | , , ,
 
For this first article looking at how to create PackMan/RiscPkg packages, I've decided to use my SunEd program as a guinea pig. Being a simple C application with no dependencies on other packages, it'll be one of the most straightforward things on my site to get working, and one of the easiest for other people to understand.
 
Read on to discover how to turn simple apps like SunEd into RiscPkg packages, and more importantly, how to automate the process.
 
 
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The state of PackMan in 2018

Posted by Jeffrey Lee on 21:30, 20/8/2018 | , , , , ,
 
In a previous article we've looked at what software is available via !PackMan. But what if you're a developer who wants to get your software listed - where do you start?

 
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Getting started with Bash on RISC OS

Posted by Mark Stephens on 08:53, 15/6/2018 |
 
There are lots of hidden treasures to try for free in PackMan (see our review from 2017). In this article we are going to go into more depth with Bash. Bash is a freely available on many systems (I use it all the time at work on Macs and Linux systems). It also provides the basis for running many other tools and automating things by writing short Bash scripts.



Once installed, you can start writing Bash directly in a single-tasking window by running the Bash App. But the best way to run it is from a terminal window. Just type the command Bash and you will be using bash.

Type in exit to return to the standard RISC OS command line.

Type in help to give you a list of commands at any time.



If you want to learn more about Bash, we recommend you start with the Wikipedia entry.

What is your favourite tool on !PackMan?
 
1 comment in the forums

Power Switching a RaspberryPi

Posted by Mark Stephens on 10:27, 28/4/2018 | ,
 
Chris Hall has been trying to make the most of power for a RISC OS based RaspberryPi for his GPS system. In his guest post , he lifts the lid on how he does this...

A Raspberry Pi can be powered by a mains adapter or by a powerbank. I found myself often pulling out the power plug to power cycle the Pi and came up with a software power switching method that would allow power to be removed under software control.



A 'power booster' board allows an internal 3.7V Lithium-Polymer battery to produce a 5.2V output and any external 5V power source will take over this rule and charge the internal battery until fully charged. Switching on and off is controlled by an 'ENABLE' input, pulled high by default. A blue LED lights if power is being supplied to the computer. With the booster board output disabled, only a minimal current is drawn from the internal battery. A red LED lights if the internal battery becomes discharged below 3V (and if a diode is fitted to the 'LBO' pad this can disable the output automatically). Fully discharging the internal battery is likely to damage it.

While the internal battery is being charged a yellow LED lights, turning green when it is fully charged. A small current drain to light the green LED to show a full charge seems enough to keep some power banks happy even whilst the unit is otherwise powered down and the internal battery fully charged.

This means the external source can be connected and disconnected without affecting the operation of the device except to extend battery life.



Power control
With no power control hardware it is difficult to ensure that the computer is not, inadvertently,turned off during a write operation to the SD card, which can corrupt the file or the whole card. My power control circuit allows power to be applied at any time by pressing the 'on' button. The 'off' button simply signals that a power off has been requested, which can be detected in software. A shutdown/restart cycle will then remove power as soon as the system has been shut down and the CMOS updated.

If software detects a 'power off' request then all it has to do (once it has completed any essential tasks) is to issue the command:

SYS "TaskManager_Shutdown",162

which will do a shutdown/restart cycle.

Doing a manual shutdown (CTRL-SHIFT-f12) and then pressing 'Restart' will also remove power (if a 'power off' request has been issued).



How Does It Work?

Software can detect the 'on' button being pressed or held down by reading the GPIO 19 line and can use this information for any purpose. The fact that the 'off' button has been pressed (and the 'on' button remains open circuit) can be detected by reading GPIO 26, meaning that 'power off' has been requested.

A little piece of software in !Boot.Choices.Boot.PreDesk sets GPIO 4 to output high (which ensures power stays on even after a 'power off' request).

During a restart cycle, before any writes are made to the SD card, the ROM modules are reset which takes GPIO 4 to high impedance: with a 'power off' request pending this will remove power.

Provided that the unit has been operating for at least six seconds (enough time for the RISC OS desktop to start), the 'off' button will pull GPIO 26 low but do nothing else. Software can detect this, complete any essential tasks and then either explicitly set GPIO 4 low (if a Witty Pi is present, this will remove power immediately) or (if not) perform a complete system shutdown using the command SYS "TaskManager_Shutdown",162 which will shutdown all applications tidily and restart RISC OS. The effect of this is to update the CMOS Ílast time onŽ setting and restart the ROM. As the ROM reinitialises, GPIO 4 becomes high impedance thus removing power.



The 'on' button has some additional functions: whilst pressed, components (R6, R7 and LED) may also be fitted to present an LED load to any external power source that will only light if the external source is healthy (this works by sensing whether Vs from the power boost board is 3.7V or 5.2V). If a voltmeter is fitted as shown, the voltage of the internal LiPo battery is displayed whilst the button is depressed. A power meter can also be connected between the power boost board and the Raspberry Pi giving a voltage, current and power consumption readout.



Battery Life
With an internal 4400mAh LiPo battery, a Raspberry Pi Zero with an OLED display and GPS module (but with no HDMI connection) uses about 170mA (at 5V) and the battery should therefore last for about (4400 x 3.7)/(170 x 5.2)h which is just over 18 hours. A 5000mAh 5V powerbank should extend this by about 28 hours.



Chris Hall's website
 
1 comment in the forums

DDE tools update released

Posted by Mark Stephens on 07:21, 6/4/2018 |
 
ROOL has released a new update for their toolset, DDE28b. As the name suggests, this is not a major update but incremental tweaks and bug fixes to the tools. Reading through the Changelogs, changes are in !CC, !DDT, !ObjAsm and !ResTest and ddt module has also been updated.

This is now the default version for new customers. Existing customers have been sent a zip with the changes to copy over the existing release.

In their email to users, ROOL also mention additional bounties for further support for ARM processors.

Tools are critical to the survival of any platform so good to see ongoing improvements on DDE.
 
Bounty link

 
4 comments in the forums

55 BBC Micro Books on CD

Posted by Mark Stephens on 07:53, 9/3/2018 | ,
 

If you are looking to experiment with BBC BASIC (or a bit of nostalgia), you should take a look at the 55 BBC Micro Books CD from Drag'N'Drop.

The disk consists of a wide range of BBC BASIC material, republished. The books themselves are included in multiple formats (PDF, HTML, Impression and EasiWriter) with the BASIC supplied as separate listings.

Many of the listings are quite short and targeted at the capabilities of the BBC range, but there is a lot of material here to explore, nicely presented. There is a wide range of programs and guides, with lots of games.




There are plenty of places to get lost, old friends to rediscover and new ones to find in this compilation of material.

The CD costs 12 pounds from Drag'N'Drop website
 
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BBC BASIC Reference Manual updated

Posted by Mark Stephens on 07:04, 12/1/2018 | ,
 
ROOL continues on its mission to bring RISC OS and its documentation up to date with a thoroughly revised and updated version of the BBC BASIC Reference Manual. This available both as a PDF in the programming documentation and as a hard copy book.

Issue 1 was published in 1992 so quite a lot has changed for this 2017 release 2. It is a fairly substantial volume (510 pages including the index). It is bang up to date, mentioning RISC OS 5.24 and BASICVFP.

The manual is nicely structured so it can be read from cover to cover as a tutorial but is also clearly structured to provide a lookup for people wanting to find a specific item of information. The book identifies 3 target readership groups:-
1. Total beginners looking to learn BBC BASIC as an introduction to computing.
2. Experienced programmers looking to learn a new language.
3. A reference guide for experienced BBC BASIC programmers who want to look-up some details.

To this end, it is split into Overview, Programming Techniques, Reference and Appendices. There are lots of little programming examples to show how commands work. There are no screenshots.

If you are dipping your toe into the programming waters, there are some simple examples and some good explanations of the technical side of programming (integers and floating point, error handling, writing structured code, binary) while there is lots of detail for more advanced developers (?, !, |, $ indirect operators, VDU commands, using the assembler). You will need additional resources to learn to write Desktop WIMP programs but it will give you a full grasp of BBC BASIC.

The book now has pride of place on my technical bookshelf and the Appendix section is becoming increasing thumbed through. What are your thoughts?

Buy the book from ROOL
 
4 comments in the forums

DDE reaches release 28 and above

Posted by Mark Stephens on 07:25, 10/11/2017 | ,
 
At the London Show, ROOL released DDE 28. DDE is a key development tool for RISC OS so it very important to see regular new releases for it.

The software was sent out to show purchasers as a time-limited link to download (I got my copy on sunday morning after the show!). You can now get it via the ROOL store.

The change logs record changes to 13 tools in the software specific to the DDE software and the readme lists changes to other software (like !srcEdit). Most of the changes are minor. For example, !AMU is now 5.32 - up from 5.31 in DDE27) and now correctly reads a timestamp). Some items have not changed in this release (for example !ABC).

There have been some major changes in the Compiler, which actually introduced a bug in compilation. This was quickly fixed with a patch release from ROOL, containing just the changed files. So you will need both to patch your existing version - hopefully ROOL have updated the original DDE28 build for new downloads.

This is quite a technical release and there is a good and detailed discussion of the technical changes on the ROOL forums. There is also an interesting discussion on the bug introduced. It is good to see the software is being evaluated and used by developers and full credit to ROOL for the quick fix.

The package also comes with a full collection of documentation in PDF format and this has all been updated to latest versions.

If you are a non-technical user, this release essentially continues to improve the software and ensure it supports the ARM platforms as well as possible. If you are looking to get into programming, it is also a fully featured collection of all the tools and documentation you need with lots of examples to get you started (and a great way to support ROOL).

ROOL store
 
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Newsround

Read article... | 3 comments in the forums

Easier video playback on RISC OS?

Read article... | 17 comments in the forums

Software migrates to the Beagleboard

Read article... | 9 comments in the forums

ROOL C Tools Get Cheaper

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RISC OS on new hardware

Read article... | 30 comments in the forums

RISC OS on OMAP - the future?

Read article... | 26 comments in the forums
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