The PowerPC based processor on the board is responsible for radio application software associated with initialization and control of the radio transceiver. This includes responsibility for configuring, monitoring and communicating with the DSP block. A number of software processes run on the processor to take care of the radio subsystem (needed for channel configuration, handover, power control etc.) a data link service provider for controlling a HDLC link off board and other maintenance applications for TTY debug and alarm monitoring.

The real time response of the platform comes from the timing demands of GSM. The PowerPC based kernel must provide real time response to multiple interrupt sources, including DSP interrupts at a frequency of 577 microseconds, GSM frame interrupts, sourced from the ASIC every 4.615 milliseconds, GSM Superframe interrupts every 6.12 seconds, HDLC interrupts and TTY interrupts.

With the above processing and interrupt handling requirements it’s clear that a real time operating system is needed. So why persist in porting or developing an in-house solution instead of going with an off the shelf option such as Linux or VxWorks? That’s a question I hope to tackle in the next article. Stay tuned….

PowerPC Kernel Implementation for GSM Radio Platform – Previous Posts

• PowerPC Kernel Implementation – Introduction

On a personal note I’m currently looking for a new position in embedded software. My LinkedIn profile has a summary of my professional and education experience www.linkedin.com/in/ralphdepping and I am happy to email my resume to any interested parties.

1. Be on Time

Although this is one of the more obvious points regarding interviews it is still worth re-stating. Allow plenty of time to find the correct location, taking into account possible traffic delays. Also make sure you know where the interview is actually taking place. One recruitment company sent me to the offices of the company instead of the hotel where the interview was being held. Fortunately the hotel was near the office and I had enough time to make the short trip and still be on time. On a related note don’t show up too early. It may make people uncomfortable to have you sitting around for a long time at reception.

2. Make a Good Last Impression

The old saying regarding the importance of “making a good first impression” also applies to “making a good last impression”. I’ll always remember a test the BBC carried out. They showed two different versions of the same interview. In the first instance the interviewee started well but finished poorly. In the second instance the interviewee started poorly but finished well. One half of the viewing public saw the first version and the other half saw the second version. The public were then asked if the interview went well for the interviewee. It turned out based on the public votes that leaving a good last impression is more important than making a good first impression.

3. Avoid Technical Jargon

Although it’s a technical interview avoid using too much jargon. The person will be more impressed with your ability to describe the work you’ve done in a clear and concise way than trying to dominate the conversation with obscure technical waffle. Remember that you may know more than the person interviewing you in a particular area but you won’t score many points by trying to show off.

4. Can I Work With This Person?

One of the key questions that both sides to an interview should be asking is “Can I work with this person?”. Ticking all of the experience and educational boxes is rarely enough to ensure a successful working environment. An interviewer will be wondering what it will be like to work with you on a daily basis. Ensure that during the interview you don’t loose sight of what the day to day working conditions will be like. Think of a couple of questions in advance that will highlight a typical working day. Is it high pressured or relaxed? Do people tend to spend lunch together or do most people just grab a sandwich and eat it at their desk? Try to relate to the people at the interview as they may end up being co-workers in the near future.

5. Do Your Homework

The most obvious aspect to this is to research the company you are applying for. However if you can find out the name of the interviewer(s) better again. It’s amazing the amount of detail that can be found these days on the Internet. Google is a great starting point, but consider searching more specialized sites such as linkedin or zoominfo If they have a relatively common name that throws up numerous results trying narrowing the search based on the company name or the geographical area the company is located in.

6. Be Prepared to Address Salary

One of the hardest questions to address in an interview can be that of salary. This is especially the case for new graduates, for whom this is probably their first experience of interviewing for a job. Make sure you’ve done your salary research. If your using a recruitment company they are often in a position to negotiate on your behalf and should have a good idea of how far a potential employer is willing to go in terms of salary.
One way of shifting the discussion and giving a potential employer more scope is to discuss the overall renumeration package. Salary is one aspect (and of course the major one) but things like pension, health insurance, gym membership and even additional holiday entitlements all add up. Recognize that taking on a new employee is a risk for the company and they want to make sure they don’t start you off on a bloated salary as it is hard to roll back from that point. If salary is becoming a major sticking point consider offering to prove your worth over a 6-12 month period. At the end of an agreed period if you’ve lived up to your own hype then the company should be willing to reward you appropriately. If not then do you really want to work there anywhere?

Tech Interview Links

• An great article from the other side of the fence, how to recognise a good programmer during an interview.
• Although some of the suggestions are, in my opinion, a little over the top i (I can’t see a HireMe book taking off in Ireland) Nailing Your Technical Interview does have some great advice on areas most of us wouldn’t naturally consider.
• Finally for those just looking for more C programming related interview questions then apparently these are some of the interview questions that Microsoft ask.

Doug Gaff, an embedded enginer with Rind River speaks highly of his time at Virginia Techn University. Sadly the University, especially internationally, will be mainly known for the terrible killings that took place there this past week. Doug’s post helpfully points to the positive aspects of the University and town of Blacksburg, in particular it’s contribution to engineering.

Damien Mulley is looking for your old mobile phones. Although not strictly related to embedded software the request is curious enough to make me wonder what he is up to, especially as the phones need to be in working order and you won’t get them back.

Finally Clare Dillon from Microsoft Ireland highlights a free one day introduction to developing software for Windows Mobile. It’s been run by Microsoft in Dublin on May 14th.

Zfone from Phil Zimmerman is continuing to take some massive strides towards acceptance by the IETF according to the VOIPSA. So as VOIPSA asks why doesn’t Skype embrace a protocol like ZRTP to deflect the criticism and suspicion surrounding it’s VoIP encryption?

Doug Gaff gives embedded engineers a scare by asking is the embedded industry dead? Embedded Processors from ExtremeTech is a great introduction to the embedded processor market (although the article is now 5 years old). Making the Pentium processor’s market share equate to practically 0% should come as some comfort to embedded engineers that are worried about the death of their industry

The Embedded Components blog allows active contribution as means of increasing your influence in the embedded market place. The blog seems to have quite a low rate of posting, but it’s still great to keep coming across embedded focused blogs.

China Daily reports that tickets for the 2008 Olympics will have embedded RFID chips in order to prevent counterfeiting. This was also done for the last football world cup.

We write code for humans, not computers. That may seem a strange statement, but when you consider that machines don’t care about the number of source files you have, the use of nice variable names, comments, white space, new lines, functions etc. then it’s clear that the main audience for the code you write is the human reader. So if you’re going to bother to write code that can be read by a human then it better be easy to understand, preferably first time. Scott Belware uses the term Soluble Code for code that can be understood first time and his short summary on the topic is excellent.
(By the way one possible exception to soluble code may be when writing assembly, but even then clear comments, spacing, multiple files etc. should still be present).

Quickly, pick a number between 1 and 20? So how “Random” was your guess? Turns out humans aren’t great at doing random and 17 is the most random number we come up with between 1 and 20.

There are few details available at the moment but from Micheál Martin’s comments it sounds like some of the work is in software engineering coupled with electronics, RF and mechanical engineering.

There has been a raft of recent announcements relating to tech jobs in Cork. It would be unfair to suggest that they are all in response to the recent job losses in Cork, coupled with an upcoming general election and the fact that the Minister for Enterprise, Trade and Employment is from Cork. No doubt these announcements would be made regardless. But it does some very coincidental.

On the subject of Windows Smartphone, Windows Mobile 6.0 comes with built in support for SD card encryption. WM 6.0 will also support remote and local wipe . Good news for the growing amounts of sensitive data being placed on smartphones.

Wouldn’t it be great to be working in Silicon Valley and be able to go the Embedded Systems Conference? You even get to hear Al Gore give the key note speech!

Jack Ganssle has some comments on comments and I don’t mean blog comments. The approach I adopt when it comes to commenting is to first of all write the function design using Program Design Language and turn the PDL into the comments.

Finally thanks to Damien Mulley for the plug on his excellent (and widely read) blog. Like many other bloggers in Ireland my interest in blogging owes a lot to his tireless (or tiring!) work.