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7425af761a
This makes the code pretty easily portable to other architectures if someone wants to make a more modern SIMM programmer. I also was pretty careful to split responsibilities of the different components and give the existing components better names. I'm pretty happy with the organization of the code now. As part of this change I have also heavily optimized the code. In particular, the read and write cycle routines are very important to the overall performance of the programmer. In these routines I had to make some tradeoffs of code performance versus prettiness, but the overall result is much faster programming. Some of these performance changes are the result of what I discovered when I upgraded my AVR compiler. I discovered that it is smarter at looking at 32-bit variables when I use a union instead of bitwise operations. I also shaved off more CPU cycles by carefully making a few small tweaks. I added a bypass for the "program only some chips" mask, because it was adding unnecessary CPU cycles for a feature that is rarely used. I removed the verification feature from the write routine, because we can always verify the data after the write chunk is complete, which is more efficient. I also added assumptions about the initial/final state of the CS/OE/WE pins, which allowed me to remove more valuable CPU cycles from the read/write cycle routines. There are also a few enormous performance optimizations I should have done a long time ago: 1) The code was only handling one received byte per main loop iteration. Reading every byte available cut nearly a minute off of the 8 MB programming time. 2) The code wasn't taking advantage of the faster programming command available in the chips used on the 8 MB SIMM. The end result of all of these optimizations is I have programming time of the 8 MB SIMM down to 3:31 (it used to be 8:43). Another minor issue I fixed: the Micron SIMM chip identification wasn't working properly. It was outputting the manufacturer ID again instead of the device ID.
60 lines
1.9 KiB
C
60 lines
1.9 KiB
C
/*
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* mcp23s17.h
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*
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* Created on: Nov 25, 2011
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* Author: Doug
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*/
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#ifndef DRIVERS_MCP23S17_H_
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#define DRIVERS_MCP23S17_H_
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#include "../hal/spi.h"
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/// A few register defines. Ordinarily I wouldn't put these in the header file
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/// because users of this module shouldn't care...but I have had to do some
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/// optimizations with the AVR to bypass the hardware abstraction layer.
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#define MCP23S17_CONTROL_WRITE(address) (0x40 | (address << 1))
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#define MCP23S17_CONTROL_READ(address) (0x40 | (address << 1) | 1)
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#define MCP23S17_IODIRA 0x00
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#define MCP23S17_IODIRB 0x01
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#define MCP23S17_IPOLA 0x02
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#define MCP23S17_IPOLB 0x03
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#define MCP23S17_GPINTENA 0x04
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#define MCP23S17_GPINTENB 0x05
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#define MCP23S17_DEFVALA 0x06
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#define MCP23S17_DEFVALB 0x07
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#define MCP23S17_INTCONA 0x08
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#define MCP23S17_INTCONB 0x09
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#define MCP23S17_IOCON 0x0A
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#define MCP23S17_IOCON_AGAIN 0x0B
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#define MCP23S17_GPPUA 0x0C
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#define MCP23S17_GPPUB 0x0D
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#define MCP23S17_INTFA 0x0E
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#define MCP23S17_INTFB 0x0F
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#define MCP23S17_INTCAPA 0x10
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#define MCP23S17_INTCAPB 0x11
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#define MCP23S17_GPIOA 0x12
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#define MCP23S17_GPIOB 0x13
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#define MCP23S17_OLATA 0x14
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#define MCP23S17_OLATB 0x15
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/// Struct representing a single MCP23S17 device
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typedef struct MCP23S17
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{
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/// The SPI device representing this MCP23S17
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SPIDevice spi;
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} MCP23S17;
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void MCP23S17_Init(MCP23S17 *mcp, GPIOPin resetPin);
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void MCP23S17_Begin(MCP23S17 *mcp);
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void MCP23S17_End(MCP23S17 *mcp);
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void MCP23S17_SetDDR(MCP23S17 *mcp, uint16_t ddr);
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uint16_t MCP23S17_DDR(MCP23S17 *mcp);
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void MCP23S17_SetOutputs(MCP23S17 *mcp, uint16_t data);
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uint16_t MCP23S17_Outputs(MCP23S17 *mcp);
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uint16_t MCP23S17_ReadInputs(MCP23S17 *mcp);
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void MCP23S17_SetPullups(MCP23S17 *mcp, uint16_t pullups);
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uint16_t MCP23S17_Pullups(MCP23S17 *mcp);
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#endif /* DRIVERS_MCP23S17_H_ */
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