标签: reference

Frequent correspondent Charles Manning shared a link to a question  on Nordic Semiconductor’s site. The entire question, verbatim, is “What BLE profile would suit a ECG signal best and is there any example code for ADC in to that profile? Have searched for a while and cant (sic) find any.”   Charles – and I – were stunned. Someone is building a critical bit of medical equipment with what appears to be limited knowledge of the communications protocol they’ll use. He is also planning to build this upon vendor-supplied reference code.   It’s probably unfair to read too much into this question, despite the possibly-chilling repercussions for users. I don’t want to knock the forums; they are a great way of sharing knowledge. Pre-Internet we all pretty much had to figure things out on our own, which was terribly inefficient. I can remember flying to vendors’ facilities to talk to chip designers to get the inside scoop on some poorly-documented or broken bit of functionality.   And, believe me, I’m all for reuse, and think it’s really our only hope of salvation as systems get bigger and more complex.   But reference code is notoriously-buggy and incomplete. It’s usually meant to show a developer how to use chip features. Most experienced developers have scars from episodes of figuring out just why some of this code doesn’t work. Some of it is simply ghastly. Charles uses a Nordic part and claims their code is a cut above the rest but is still just reference code.   The person who phrased this question may be an extremely competent developer who will analyze the code before using it. But this is a symptom of two problems with the industry today.   The first is the aforementioned often-crummy quality of vendor-supplied code. In some cases it’s so bad a semiconductor company will put a large team of their own engineers into a customer site to help get a product to market. Of course, this only happens for those buying enormous numbers of chips so the little folks, or even those buying hundreds of thousands, are stuck.   In some cases I know that the work these engineers do never makes it back into the reference code supplied to everyone else. There’s never time to address any issue other than the immediate crisis, so doing an update is out of the question.   One has to have some sympathy for the vendors; after all, their mission is to sell chips. Reference code is free and therefore perceived as a loss leader. The stuff has to exist to push silicon out the door, but never gets the attention it needs. Modern MCUs are really complex. Even the bus fabric can baffle. Peripherals run in innumerable modes. Hundreds or even thousands of registers have to be set exactly right. Datasheets run 500, 1000 or more pages today. Reference software really can’t address every mode and configuration. The cost to develop this stuff is enormous, the price is zero.   The second problem is the perennial issue of time to market. Customers simply don’t have the time to figure out the nuances of handling all of these peripherals so rightly want solid code they can drop their applications on top of. Reusable reference code is a solution. If this were a perfect world, reuse would be at the object code level, all of the reused code would be qualified, and customers would have complete confidence in the code.   One wonders with the explosion of IoT devices coming our way if this problem will only get worse.   Unfortunately, there’s a subtle meta-problem as well. Suppose a semiconductor vendor builds reference code that is absolutely perfect. No bugs, brilliantly documented and a testament to fine software engineering practices. Who would believe them? Decades of problems has create a general distrust. How would a vendor convince the skeptical that, now, for sure, they have produced what we really want?   When it comes to reuse it pays to think about the pyramids. They were built on incredibly strong foundations. In the firmware world, all too often that’s inverted.   What is your experience with reference code?

I recently heard from the folks at Maxim , who are touting a new reference design called the Alameda -- a flexible, high-accuracy 4-channel bipolar analog output that is targeted at industrial automation applications.   Now, I fully understand the advantages of using a reference design, especially ones like the Alameda. It includes fully tested schematics, layout files, and firmware that are available for immediate use and/or customization. In addition to reducing risk and speeding design, this particular design is claimed to use integrated parts that reduce number of components by 33% compared to competitive designs.   I also understand that creating such a design involves the expenditure of time and money. One could certainly argue that such a design is a valuable commodity and that its creators deserve recompense.   On the other hand, I think this point of view could be better argued by someone who had created the reference design as a standalone activity. However, the fact is that actually implementing this reference design involves using a bunch of Maxim's parts as illustrated below:     As we see, this design boasts a MAX17498B flyback controller, a MAX1659 LDO, a MAX6216 voltage reference, a MAX5154 quad DAC, four MAX15500 signal conditioners, and a MAX14850 data isolation device. The way I've always understood the reference design concept is as an unspoken agreement along the lines of, "We show you how to do it, and then you do it using our components."   The bottom line was that I was a bit surprised to learn that there was a cost involved with regard to the Alameda reference design. I was even more surprised to be told: "Pricing is available on request." I bounced around the Maxim website to discover that the price of this reference design is $95 and the availability is "TBD."** (Following the ** leads us to a note saying "Please submit a quote to obtain lead-time for this part.")   I'm not sure what to think. First of all, I don’t like being tempted with a reference design and then being told that I have to submit a quote to learn what the lead-time is going to be.   Hang on a moment. I think I understand. The Alameda isn’t just schematics, layout files, and firmware -- it also includes a circuit board containing a physical implementation of the design, thereby allowing you actually to test the design in your main industrial control system. Well, that certainly makes more sense, and it also explains the price associated with this reference design and associated sub-system.   OK, so if there is a hardware portion of the reference design, then I can understand there being a cost involved. But what about a non-hardware reference design -- should this also come with a cost involved or -- if using the design involves your purchasing that vendor's components -- is it more appropriate for the reference design to be provided for free?

半导体IC的替换表： Product P/N of BL Description Packages Cross Reference LDO BL1117 1A SOT-223/TO-252 1117 Any BL1085 3A TO-263/TO-252/TO-220 1085 Any BL1084 5A TO-263/TO-252/TO-220 1084 Any BL8551 150mA/24Vin SOT-89-3 HT71xx/75xx Holtek BL8503 BL8552 250mA SOT-89-3/SOT-23-3/TO-92 HT73xx Holtek 300mA RT9161 RichTek XC62FP TOREX XC6206 TOREX BL8563 BL8555 300mA SOT-23-5A S-1112 SII 150mA R1114 RICOH XC6204/6209/6221/6219 TOREX RT9167/9193 RichTek LP3985 NS SOT-23-5B S-1122 SII BL8560 Dual 150mA/ch SOT-23-6-D XC6401 TOREX SOT-23-6-C S-1711 SII BL8566 Dual 300mA/ch SOT-23-6 RT9011/9182 RichTek BL8553 400mA SOT-89-3 XC6203 TOREX BL8558 500mA SOT-23-5 RT9167A RichTek DC-DC BL8530 Internal MOSFET SOT-23-5/SOT-89-3 RT9261B RichTek S-8351 SII XC6371/72/73 TOREX RCR3132 誉坤 BL8530C External MOSFET SOT-23-5/SOT-23-3 RT9261A RichTek S-8352 SII W-LED Driver BL8508 BOOST SOT-23-5 LT1937 Linear RT9271 RichTek RT9284 RichTek BL8580 3 Channel SOT-23-6 RT9302 RichTek AMC7110 ADD BL8581 4 Channel SOP-8 AMC7111 ADD Reset BL8506 SOT-23-3/SOT-89-3 S-808 SII S-1000    SII XC61C TOREX R3111 RICOH HT ？ Holtek BL8509 200ms SOT-23-3 S-801 SII XC61F TOREX R3130N RICOH MAX803/809/810 MAXIM SGM803/809 SGMC STM809 ST Analog Switch BL4684 双路 /SPDT CSP-10 MAX4684 MAXIM BL1554 四路 /SPDT ？ Audio PA BL6212 BL6290 AB 类 CSP9/MSOP8 LM4990/LM4890 NS CP2290 启攀微 Chiphomer ft690 方泰 Fangtek BL6211 AB 类 / 全差分 MSOP8 CP2297 启攀微 Chiphomer BL6311 D类 CSP9 TPA2010 TI NCP2820 Onsemi BL6305 D类 MSOP8/SOP8/DFN8 TPA2005 TI BL34119 SOP8/TSSOP8/DIP8 MC34119 MOTO BL6217 2 * 5W （立体声） TDA1517 PHILIPS Touch BL2046 4-Wire/Resistive QFN-16 TSC2046 TI MT6301 MTK 电能计量 BL6503 单相 SSOP24 ADE7755 ADI MOSFET BLV640 200V/18A TO-220 FDP18N20 FAIRCHILD