Apple-1-Tools
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apple1-videocard-lib
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nano fastwrite attempt

This commit is contained in:
nino-porcino 2022-02-28 14:28:59 +01:00
parent 44c38afcd7
commit b9c5586b20
1 changed files with 58 additions and 19 deletions
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77
demos/sdcard/apple1_sdcard/apple1_sdcard.ino
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@ -1,11 +1,3 @@
#include <Regexp.h>
#include <SPI.h>
#include "SdFat.h"
SdFat SD;
#define SD_CS_PIN SS
/*
+-----------+ +-----------------+
| | | ARDUINO |
@ -26,6 +18,44 @@ SdFat SD;
+-----------+ +-----------------+
*/
/*
PORT ASSIGNMENT FOR FAST READ/WRITE
===================================
BIT 0: PORTD[2]
BIT 1: PORTD[3]
BIT 2: PORTD[4]
BIT 3: PORTD[5]
BIT 4: PORTD[6]
BIT 5: PORTD[7]
BIT 6: PORTB[0]
BIT 7: PORTB[1]
MCU_STROBE: PORTC[0]
CPU_STROBE: PORTC[1]
in Verilog syntax: data = { PORTB[1:0], PORTD[7:2] };
*/
#define FASTWRITE 1
#ifdef FASTWRITE
#define get_cpu_strobe ((PORTC >> 1) & 1)
#define set_mcu_strobe(c) PORTC = (PORTC & 0xFE) | (c)
#else
#define get_cpu_strobe digitalRead(CPU_STROBE)
#define set_mcu_strobe(c) digitalWrite(MCU_STROBE,(c))
#endif
#include <Regexp.h>
#include <SPI.h>
#include "SdFat.h"
SdFat SD;
#define SD_CS_PIN SS
// pin definitions
#define BIT0 2
@ -42,17 +72,17 @@ SdFat SD;
#define MCU_STROBE 14
#define CPU_STROBE 15
// indicates that a timeout occurred during wait()
// indicates that a timeout occurred during wait_cpu_strobe()
int TIMEOUT = 0;
void wait(int pin, int value) {
void wait_cpu_strobe(int value) {
unsigned long start_time = millis();
unsigned long elapsed;
if(TIMEOUT) return;
while(digitalRead(pin) != value) {
while(get_cpu_strobe != value) {
elapsed = millis() - start_time;
if(elapsed > 500) {
TIMEOUT = 1;
@ -104,9 +134,12 @@ int receive_byte_from_cpu() {
// both strobes are 0
// CPU deposits data byte and sets strobe high
wait(CPU_STROBE, HIGH);
wait_cpu_strobe(HIGH);
// read the data byte
#ifdef FASTWRITE
int data = ((PORTB & 0x03)<<6) | (PORTD >> 2); // data = { PORTB[1:0], PORTD[7:2] }
#else
int data =
(digitalRead(BIT0) << 0) |
(digitalRead(BIT1) << 1) |
@ -116,15 +149,16 @@ int receive_byte_from_cpu() {
(digitalRead(BIT5) << 5) |
(digitalRead(BIT6) << 6) |
(digitalRead(BIT7) << 7);
#endif
// after reading the byte, MCU sets strobe high
digitalWrite(MCU_STROBE, HIGH);
set_mcu_strobe(HIGH);
// CPU now sets strobe low
wait(CPU_STROBE, LOW);
wait_cpu_strobe(LOW);
// and MCU sets strobe low
digitalWrite(MCU_STROBE, LOW);
set_mcu_strobe(LOW);
return data;
}
@ -137,6 +171,10 @@ void send_byte_to_cpu(int data) {
// both strobes are 0
// put byte on the data port
#ifdef FASTWRITE
PORTB = (PORTB & 0xFC) | ((data >> 6) & 0x03); // PORTB[1:0] = data[7:6];
PORTD = (PORTD & 0x03) | (data << 2); // PORTD[7:2] = data[5:0];
#else
digitalWrite(BIT0, data & 1);
digitalWrite(BIT1, data & 2);
digitalWrite(BIT2, data & 4);
@ -145,18 +183,19 @@ void send_byte_to_cpu(int data) {
digitalWrite(BIT5, data & 32);
digitalWrite(BIT6, data & 64);
digitalWrite(BIT7, data & 128);
#endif
// after depositing data byte, MCU sets strobe high
digitalWrite(MCU_STROBE, HIGH);
set_mcu_strobe(HIGH);
// wait for CPU to set strobe high
wait(CPU_STROBE, HIGH);
wait_cpu_strobe(HIGH);
// tells CPU byte we are finished
digitalWrite(MCU_STROBE, LOW);
set_mcu_strobe(LOW);
// wait for CPU to set strobe low
wait(CPU_STROBE, LOW);
wait_cpu_strobe(LOW);
}
// *********************************************************************************************