Wiki source code of Front I/O

Version 7.3 by Kevin Wiki on 2024/07/05 09:31

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
5.2	9	[[image:xserve io main cable and PCB pinout.drawio.png\|\|alt="xserve io main cable pinout.drawio.png"]]
1.1	10
3.3	11	(% class="wikigeneratedid" %)
7.2	12	[[attach:xserve io main cable and PCB pinout.drawio.svg\|\|target="_blank"]]
1.1	13
4.2	14	(% class="wikigeneratedid" %)
	15	This cable allows us to communicate with 4 chips using two data lines, audio & service switch, case switch and (yet to be documented) compute LEDs
	16
1.3	17	= How we got here =
1.1	18
1.3	19	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	20
1.3	21	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	22
1.3	23	== Finding i2c chip address ==
1.1	24
1.3	25	=== SAA1064T ===
1.1	26
1.3	27	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.
	28
	29	=== PCA9554 ===
	30
	31	asdf
	32
	33	=== Code example finding i2c addresses ===
	34
	35	We can test the following addresses manually or use the following code snippet:
	36
	37	{{code language="C++"}}
	38	/*I2C_scanner
	39	This sketch tests standard 7-bit addresses.
	40	Devices with higher bit address might not be seen properly.*/
	41
	42	#include <Wire.h>
	43
	44	void setup() {
	45	Wire.begin();
	46
	47	Serial.begin(9600);
	48	while (!Serial);
	49	Serial.println("\nI2C Scanner");
	50	}
	51
	52	void loop() {
	53	byte error, address;
	54	int nDevices;
	55
	56	Serial.println("Scanning...");
	57
	58	nDevices = 0;
	59	for (address = 1; address < 127; address++ ) {
	60	Wire.beginTransmission(address);
	61	error = Wire.endTransmission();
	62
	63	if (error == 0) {
	64	Serial.print("I2C device found at address 0x");
	65	if (address < 16)
	66	Serial.print("0");
	67	Serial.print(address, HEX);
	68	Serial.println(" !");
	69
	70	nDevices++;
	71	}
	72	else if (error == 4) {
	73	Serial.print("Unknown error at address 0x");
	74	if (address < 16)
	75	Serial.print("0");
	76	Serial.println(address, HEX);
	77	}
	78	}
	79	if (nDevices == 0)
	80	Serial.println("No I2C devices found\n");
	81	else
	82	Serial.println("done\n");
	83
	84	delay(5000);
	85	}
	86	{{/code}}
	87
	88	== i2c multiplexing with TCA9548 ==
	89
	90	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.
	91
	92	=== Code example finding i2c ports ===
	93
	94	To verify wiring, connection, output ports and device addresses run the following script:
	95
	96	{{code language="c++"}}
	97	/**
	98	* TCA9548 I2CScanner.ino -- I2C bus scanner for Arduino
	99	*
	100	* Based on https://playground.arduino.cc/Main/I2cScanner/
	101	*
	102	*/
	103
	104	#include "Wire.h"
	105
	106	#define TCAADDR 0x70
	107
	108	void tcaselect(uint8_t i) {
	109	if (i > 7) return;
	110
	111	Wire.beginTransmission(TCAADDR);
	112	Wire.write(1 << i);
	113	Wire.endTransmission();
	114	}
	115
	116
	117	// standard Arduino setup()
	118	void setup()
	119	{
	120	while (!Serial);
	121	delay(1000);
	122
	123	Wire.begin();
	124
	125	Serial.begin(9600);
	126	Serial.println("\nTCAScanner ready!");
	127
	128	for (uint8_t t=0; t<8; t++) {
	129	tcaselect(t);
	130	Serial.print("TCA Port #"); Serial.println(t);
	131
	132	for (uint8_t addr = 0; addr<=127; addr++) {
	133	if (addr == TCAADDR) continue;
	134
	135	Wire.beginTransmission(addr);
	136	if (!Wire.endTransmission()) {
	137	Serial.print("Found I2C 0x"); Serial.println(addr,HEX);
	138	}
	139	}
	140	}
	141	Serial.println("\ndone");
	142	}
	143
	144	void loop()
	145	{
	146	}
	147	{{/code}}
2.2	148
3.1	149	== SAA1064T data for driving center IO LED stack ==
2.5	150
7.3	151	Center IO stack is a stack of 24 LED's, 23 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.
2.5	152
	153	{{code language="C++"}}
	154	void fillColumns() {
	155	Serial.println("filling columns");
	156	Wire.beginTransmission(saa1064);
	157	Wire.write(1);
	158	Wire.write(0x7F); // 127 - 1111111
	159	Wire.write(0x7F); // 127 - 1111111
	160	Wire.write(0x7F); // 127 - 1111111
	161	Wire.write(0x1F); // 31 - 11111
	162	Wire.endTransmission();
	163
	164	colsFilled = 1;
	165	}
	166	{{/code}}
	167
	168	(% class="wikigeneratedid" %)
7.3	169	~-~- Here the last byte we send only is 5 bits since we only have 5 LEDs instead of 6 to address (total of 24). Also note that we start the transmission with a single bit. ~-~-
2.5	170
2.2	171	== Pinouts voltages from MLB ==
	172
	173	Powered off:
	174
	175	* PWR fail LED - 0.00 V
2.4	176	* UID LED - 4.5V
2.2	177	* OH/Fan fail LED - 4.72 V
	178	* NIC1 LED - 0.8 - 2.6 V
	179	* NIC2 LED - 2.95 V
2.4	180	* UID SW - 2.8V
2.2	181	* HDD LED - 0.00 V
2.4	182	* Power LED P3V3 - 0.00V
2.2	183	* Power LED - 0.00 V after unplug grows
	184
	185	Powered on:
	186
	187	* PWR tail LED - 3.47 V
2.4	188	* UID LED - 4.85V
2.2	189	* OH/Fan failed LED - 5 V
	190	* NIC 1 LED - 1.2 - 2.9 V
	191	* NIC 2 LED - 3.2 V
2.3	192	* UID SW - 3V
2.2	193	* HDD LED - 3 V
2.3	194	* Power LED P3V3 - 3.30V
2.2	195	* Power LED - 0.87 V
	196
	197
1.1	198	)))
	199
	200
	201	(% class="col-xs-12 col-sm-4" %)
	202	(((
	203	{{box title="Contents"}}
	204	{{toc/}}
	205	{{/box}}
	206
	207	[[image:[email protected]]]
	208	//Figure 1: [[Sea>>https://commons.wikimedia.org/wiki/File:Isle_of_Icacos_II.jpg]]//
	209
	210	[[image:[email protected]]]
	211	//Figure 2: [[Waves>>https://commons.wikimedia.org/wiki/File:Culebra_-_Playa_de_Flamenco.jpg]]//
2.2	212
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2.5	218
1.1	219	)))
	220	)))

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