Wiki source code of Front I/O

Version 3.3 by Kevin Wiki on 2024/07/04 23:07

version	line-number	content
1.1	1	(% class="row" %)
	2	(((
	3	(% class="col-xs-12 col-sm-8" %)
	4	(((
1.2	5	= Pinout =
1.1	6
1.2	7	There is a single cable that controls four parts, each half side of I/O LED and center column of blue LEDs.
1.1	8
3.3	9	[[image:xserve io main cable pinout.drawio.png]]
1.1	10
3.3	11	(% class="wikigeneratedid" %)
	12	[[attach:xserve io main cable pinout.drawio.svg\|\|target="_blank"]]
1.1	13
1.3	14	= How we got here =
1.1	15
1.3	16	Measure out the ground and power signals by comparing with other chips on board. E.g. we find [SAA1064T] datasheet, locate the GND (Vee) and 5V (Vcc) and measure connectivity (0 ohm resistance) between chip pins and cable pins. This gives us pins GND 2 & 8 and PWR 16 & 22.
1.1	17
1.3	18	We keep doing this for SCL & SDA pins on SAA1064T chip and find pins 14 & 15 and 20 & 21 are I2C clock and data pins for each chip.
1.1	19
1.3	20	== Finding i2c chip address ==
1.1	21
1.3	22	=== SAA1064T ===
1.1	23
1.3	24	Reading the datasheet for SAA1064T chip we find that: "//This results in the corresponding valid addresses HEX 70, 72, 74 and 76 for writing and 71, 73, 75 and 77 for reading. All other addresses cannot be acknowledged by the circuit".// Giving us a clue what we are looking for, i2c addresses 0x70, 0x72 or 0x74.
	25
	26	=== PCA9554 ===
	27
	28	asdf
	29
	30	=== Code example finding i2c addresses ===
	31
	32	We can test the following addresses manually or use the following code snippet:
	33
	34	{{code language="C++"}}
	35	/*I2C_scanner
	36	This sketch tests standard 7-bit addresses.
	37	Devices with higher bit address might not be seen properly.*/
	38
	39	#include <Wire.h>
	40
	41	void setup() {
	42	Wire.begin();
	43
	44	Serial.begin(9600);
	45	while (!Serial);
	46	Serial.println("\nI2C Scanner");
	47	}
	48
	49	void loop() {
	50	byte error, address;
	51	int nDevices;
	52
	53	Serial.println("Scanning...");
	54
	55	nDevices = 0;
	56	for (address = 1; address < 127; address++ ) {
	57	Wire.beginTransmission(address);
	58	error = Wire.endTransmission();
	59
	60	if (error == 0) {
	61	Serial.print("I2C device found at address 0x");
	62	if (address < 16)
	63	Serial.print("0");
	64	Serial.print(address, HEX);
	65	Serial.println(" !");
	66
	67	nDevices++;
	68	}
	69	else if (error == 4) {
	70	Serial.print("Unknown error at address 0x");
	71	if (address < 16)
	72	Serial.print("0");
	73	Serial.println(address, HEX);
	74	}
	75	}
	76	if (nDevices == 0)
	77	Serial.println("No I2C devices found\n");
	78	else
	79	Serial.println("done\n");
	80
	81	delay(5000);
	82	}
	83	{{/code}}
	84
	85	== i2c multiplexing with TCA9548 ==
	86
	87	We have two sets of chips, one for left and one for right where we have two different i2c chips on each side for controlling lights. Since the chips controlling their respective parts have the same address for each side, we can't distinguish them from each other. To handle this we use a i2c multiplexer to selectively communicate with one half at a time, switching TCA9548 between two different output ports.
	88
	89	=== Code example finding i2c ports ===
	90
	91	To verify wiring, connection, output ports and device addresses run the following script:
	92
	93	{{code language="c++"}}
	94	/**
	95	* TCA9548 I2CScanner.ino -- I2C bus scanner for Arduino
	96	*
	97	* Based on https://playground.arduino.cc/Main/I2cScanner/
	98	*
	99	*/
	100
	101	#include "Wire.h"
	102
	103	#define TCAADDR 0x70
	104
	105	void tcaselect(uint8_t i) {
	106	if (i > 7) return;
	107
	108	Wire.beginTransmission(TCAADDR);
	109	Wire.write(1 << i);
	110	Wire.endTransmission();
	111	}
	112
	113
	114	// standard Arduino setup()
	115	void setup()
	116	{
	117	while (!Serial);
	118	delay(1000);
	119
	120	Wire.begin();
	121
	122	Serial.begin(9600);
	123	Serial.println("\nTCAScanner ready!");
	124
	125	for (uint8_t t=0; t<8; t++) {
	126	tcaselect(t);
	127	Serial.print("TCA Port #"); Serial.println(t);
	128
	129	for (uint8_t addr = 0; addr<=127; addr++) {
	130	if (addr == TCAADDR) continue;
	131
	132	Wire.beginTransmission(addr);
	133	if (!Wire.endTransmission()) {
	134	Serial.print("Found I2C 0x"); Serial.println(addr,HEX);
	135	}
	136	}
	137	}
	138	Serial.println("\ndone");
	139	}
	140
	141	void loop()
	142	{
	143	}
	144	{{/code}}
2.2	145
3.1	146	== SAA1064T data for driving center IO LED stack ==
2.5	147
	148	Center IO stack is a stack of 23 LED's, 22 blue and 1 green for ethernet activity. These are duplicated next to each other and driven by each their SAA1064T chips. Earlier we found the i2c address and just by playing around figured out that 4 segments of 1 byte binary values are used to set ship register.
	149
	150	{{code language="C++"}}
	151	void fillColumns() {
	152	Serial.println("filling columns");
	153	Wire.beginTransmission(saa1064);
	154	Wire.write(1);
	155	Wire.write(0x7F); // 127 - 1111111
	156	Wire.write(0x7F); // 127 - 1111111
	157	Wire.write(0x7F); // 127 - 1111111
	158	Wire.write(0x1F); // 31 - 11111
	159	Wire.endTransmission();
	160
	161	colsFilled = 1;
	162	}
	163	{{/code}}
	164
	165	(% class="wikigeneratedid" %)
	166	Here the last byte we send only is 5 bits since we only have 5 LEDs instead of 6 to address (total of 23). Also note that we start the transmission with a single bit.
	167
2.2	168	== Pinouts voltages from MLB ==
	169
	170	Powered off:
	171
	172	* PWR fail LED - 0.00 V
2.4	173	* UID LED - 4.5V
2.2	174	* OH/Fan fail LED - 4.72 V
	175	* NIC1 LED - 0.8 - 2.6 V
	176	* NIC2 LED - 2.95 V
2.4	177	* UID SW - 2.8V
2.2	178	* HDD LED - 0.00 V
2.4	179	* Power LED P3V3 - 0.00V
2.2	180	* Power LED - 0.00 V after unplug grows
	181
	182	Powered on:
	183
	184	* PWR tail LED - 3.47 V
2.4	185	* UID LED - 4.85V
2.2	186	* OH/Fan failed LED - 5 V
	187	* NIC 1 LED - 1.2 - 2.9 V
	188	* NIC 2 LED - 3.2 V
2.3	189	* UID SW - 3V
2.2	190	* HDD LED - 3 V
2.3	191	* Power LED P3V3 - 3.30V
2.2	192	* Power LED - 0.87 V
	193
	194
1.1	195	)))
	196
	197
	198	(% class="col-xs-12 col-sm-4" %)
	199	(((
	200	{{box title="Contents"}}
	201	{{toc/}}
	202	{{/box}}
	203
	204	[[image:[email protected]]]
	205	//Figure 1: [[Sea>>https://commons.wikimedia.org/wiki/File:Isle_of_Icacos_II.jpg]]//
	206
	207	[[image:[email protected]]]
	208	//Figure 2: [[Waves>>https://commons.wikimedia.org/wiki/File:Culebra_-_Playa_de_Flamenco.jpg]]//
2.2	209
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2.5	215
1.1	216	)))
	217	)))

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