An NES cartridge in its most basic form is a surprisingly simple device, it contains two ROMs hosting all the code and assets of its game, and a Nintendo code chip that provided what was a state-of-the-art consumer DRM system for the 1980s. Decades later its inner workings have been extensively reverse-engineered, and there have been quite a few custom and reprogrammable cartridge designs produced.
This hasn’t stopped [Troy Denton] and [Brad Taylor] making a cartridge of their own though, and the result of their labours is a fully USB reprogrammable cartridge for the Nintendo Entertainment System. It provides nonvolatile storage and is a simpler design than you might expect, using a pair of 1 megabit Flash chips and emulating Nintendo’s DRM with an ATtiny microcontroller.
In itself it’s an interesting enough design, but what makes the write-up stand out is the description of having the boards manufactured by a PCBA service, and their subsequent debugging. A surface-mount micro USB socket that shorted out the USB power required a bit of rework to place Kapton tape beneath it, while another clever patch uses the NES clock signal to provide a read-only line for the memory. It’s also interesting to hear about their manual “crowdfunding” approach which was to ask around if anyone else wanted one so they could bring unit cost down by producing more cartridges.
If you’re interested in the NES DRM system, it’s a subject we’ve touched on in the past.
[Pete] was building a hot tub controller, using a WEMOS board based on the venerable ESP8266. After assembly, the board was plugged into USB and [Pete] hit the flash button. No dice. Investigation with some terminal software indicated a checksum error.
Assuming the board was dead, [Pete] grabbed another — and suffered the same problem. The WEMOS boards wouldn’t program, but other boards had no issues. Sensing that something may be amiss, further research was in order. A forum post turned up discussing different programming modes for the ESP8266.
It turns out that there are different types of flash used with the ESP8266, and the correct programming mode must be selected for a given hardware setup. These modes are known as DIO and QIO, meaning “dual IO” and “quad IO” respectively. This refers to the number of IO line used to talk to the flash memory. There are also further modes, known as DOUT and QOUT. It’s important to identify the modes supported by the flash chip on board, by looking at the datasheet. Obviously this can be difficult on some pre-built modules, so experimentation is the key here.
With the wrong mode selected, writes to the flash will fail, and reading back will turn up a checksum error. It’s a simple matter of changing a line in the make file and trying different modes, to see which one works. This forum post has a more in-depth coverage of the issue.
By choosing different flash memory parts and selecting the DIO or DOUT modes, it’s actually possible to free up more GPIO pins as well. This knowledge is handy when optimizing ESP8266 designs for memory speed or maximum IO flexibility. It’s a good lesson that it always pays to look at the datasheet to get the best out of your parts.
You may still have some luck getting those selfies off of your SD card, even if it will no longer mount on your computer. [HDD Recovery Services] shows us a process to directly access the NAND memory of a faulty micro SD card to recover those precious files you thought about backing up but never got around to.
On a Micro SD card you may have noticed there are two slightly longer pins than the rest. These are VSS and VCC pins. As long as they are not a dead short between the two the SD card controller isn’t completely trashed and we can go ahead and get into that little sucker. With a bit of know how — along with sandpaper, enameled wire, and a NAND reader — an image of your lost data can be recovered with a bit of patience and some good soldering skills.
Working your way down from a relatively high grit sand paper, slowly sand away the plastic on the underside of the SD card until you can clearly see the copper traces hidden away inside. Then solder your enameled wire onto the small solder pads to hook it up to a NAND reader and you should be able to read the data that was previously unreachable via conventional means. Of course you’re still going to need to make sense out of the NAND dump. That’s a topic for a different article.
If you ever find yourself in need of an SD card recovery tool you could always roll your own DIY NAND reader. We will likely give this process a try just to play round with the concept. Hopefully we’ll never need to do SD card recovery!
Continue reading “Recover Your Broken SD Card Selfies By Your Selfie”
When [sticilface] started using the Arduino IDE to program an ESP8266, he found he was running out of RAM quickly. The culprit? Strings. That’s not surprising. Strings can be long and many strings like prompts and the like don’t ever change. There is a way to tell the compiler you’d like to store data that won’t change in program storage instead of RAM. They still eat up memory, of course, but you have a lot more program storage than you do RAM on a typical device. He posted his results on a Gist.
On the face of it, it is simple enough to define a memory allocation with the PROGMEM keyword. There’s also macros that make things easier and a host of functions for dealing with strings in program space (basically, the standard C library calls with a _P suffix).
Continue reading “Save ESP8266 RAM With PROGMEM”
If you’ve ever corrupted a flash memory on a power failure, you’ll be glad to hear that the ESP8266 SDK implements a very secure and almost infallible read/write management for its flash memory. The catch: It’s also very wasteful. For a single memory block of stored data, three memory blocks of physical flash memory are occupied. [Peter Scargill] enlightens us with a better solution.
Continue reading “Overhauling The ESP8266’s Flash Memory Handling”
An SD card is surely not an enterprise grade storage solution, but single board computers also aren’t just toys anymore. You find them in applications far beyond the educational purpose they have emerged from, and the line between non-critical and critical applications keeps getting blurred.
Laundry notification hacks and arcade machines fail without causing harm. But how about electronic access control, or an automatic pet feeder? Would you rely on the data integrity of a plain micro SD card stuffed into a single board computer to keep your pet fed when you’re on vacation and you back in afterward? After all, SD card corruption is a well-discussed topic in the Raspberry Pi community. What can we do to keep our favorite single board computers from failing at random, and is there a better solution to the problem of storage than a stack of SD cards?
Continue reading “Single Board Revolution: Preventing Flash Memory Corruption”
We just got through reviewing MicroPython on the ESP8266, and one of the main takehomes is that our ESP modules need more flash memory. You may be in the same boat — the earliest (and cheapest) modules on the market only had 512 kB of flash. For over-the-air programming, or to give you some more space for fancier programs, you’re going to want 1 MB or even 4 MB.
The solution? Just buy a new flash chip and solder it on. This is especially easy if you’ve got an ESP-01, ESP-03, or ESP-11 modules where the flash chip is exposed. Desolder, resolder, done. It can be a little trickier for those modules with a tin can around chips, but that’s nothing that a little hot air can’t fix. See the video embedded below for a good walk-through.
Continue reading “Your ESP8266 Needs More Memory”