Ben Heck's Portable N64 Part 2

In this episode, Ben miniaturizes the controller using an Arduino Pro Micro and Playstation Vita analog stick, embeds the RAM expansion, and works on a case design with a nod to the Nintendo Switch. The N64 is notorious for being difficult to hack as it’s easily damaged due to all the rewiring required to make it smaller! Visit the Ben Heck page on element14 at: http://bit.ly/2lwvIUE

The Ben Heck Team continues working on the N64 portable. In a previous episode, they worked on the memory and the power. In today’s episode they are going to try to shrink down the controller so it will fit in the case, and then they’ll also add the memory expansion that goes into the controller inside the system. Once all that is done they’ll have an idea how the system will be shaped so they can begin designing a case for it. The N64 is difficult to hack because it’s easy to damage and there are a lot of things you have to rewire in order to make it remotely smaller.

The N64 is notorious for its analog stick because it tends to wear out quickly and has a huge analog stick package. It doesn’t work the same way as any other console analog stick, such as the Playstation or the Xbox. It uses optical encoders, like a mouse would, and the stick wears out quickly. It also has a hug e analog stick package. The position of the analog stick is determined by change so it’s basically like 2 mice wheels controlling X and Y.

After taking apart the controller, Ben hooks the controller board to an oscilloscope. He applies 3V to the analog stick which powers up the optical encoders. It’s not really an encoder, it’s more like two optics! Like an old school mouse, when they change, you know what direction the sticks going in. The order in which they change tells the controller which way the stick is being moved. You’re moving an encoder wheel back and forth waiting, opening little slits for light to go through, in a certain order. All other analog sticks get voltages off a pair of potentiometers.

So what you’d have to do with an analog stick encode is keep track of where it is, its position, and you would only send the pulses when it changes position. You’d also have to have some dead space as there is only 160 steps in each direction for the Nintendo. That’s 160 steps in either direction perpendicular with 80 steps coming in both directions from center. Ben uses this information to replicate the N64 analog stick with a more traditional analog stick and an Arduino Pro Mini. They can run this Atmel chip off the same 3.3 V line powering the N64 controller. Next, he wires the microcontroller into the N64 controller to see if he can reproduce the kind of pulses coming off the N64 analog stick.

He attaches some disconnects to the Arduino board as the board he’s using can run at 5V but the N64 controller runs at 3V. That way it’s only sending 3V signals to the Nintendo Chip so as not to damage anything. MCU’s can run at multiple voltages, but this can affect their max speed so check your datasheets. He experiments with various analog sticks attached with a microcontroller to see if he can fine an adequate replacement for the N64 analog stick. He finds a suitable analog stick from a PSP.

Next, Ben desolders the connector for expansion memory card to find out what the pinout is, and make a decision on what to do with the controller board. He removes the memory chip from the memory card as well as the controller’s microprocessor and creates his own custom board that will house these chips. Using Felix’s help Ben creates a smaller replacement for the controller. The Nintendo chip is put on its very own breakout board. He then combines the Nintendo controller chip with the memory card chip.

Ben rewires everything from the memory pack to the controller’s integrated circuit and he moves most of the passives off the original controller’s circuit board onto the circuit board that Felix etched. He’s able to get it to write and read the memory card correctl