Well, as promised in my last CPC2 post, I finished the next build of the CPC2 board and learned a lot of things during the process. Somethings worked, some things didn’t, but every build is giving me a wealth of knowledge of product design, fault diagnosis and rectification work. Yes, de-solder braid really was my best friend in this build!
As a brief reprieve from my main CPC2 project, I sidetracked into Arduino programming to solve a problem on the CPC2. I need to create an interface to a memory card, with only two wires. To do this, I’m going to use an Atmel (Microchip) ATtiny841 to interface between the memory card SPI interface and a two-wire serial UART. To program this device without spending heaps of money on a dedicated programmer, I’ll use an Arduino to program the Tiny. This post covers setting up an Arduino to write a bootloader into another Arduino or Atmel chip. To test this process, I used an Freetronics EtherTen to program a Freetronics Eleven that had a damaged bootloader. I’m using version 1.8.5 of the Arduino IDE.
I’ll start with a confession. While I’ve had some success with FPGAs, I managed this despite not understanding some of the basics, such as system design constraints, particularly in Quartus. This post covers both my research into system design/timing constraints and the result of the byte cache that sits on top of the SDRAM controller. I’ll break with my tradition and save the screen grab for the end.
Cache (Screen) Grab (Click for large)
This screen grab shows one of the key process steps in the caching controller, the cache line replacement. The red bracket indicates the cache i/o ports and some key internal state variables, and the blue bracket indicates the data cache i/o ports on the dual-port ram. Continue reading