Skip to content

Commit 07fbcc9

Browse files
techy-robottechy-robot
committed
Added support for MA735
This is largely based off of the code for MA730, with some additional functions to support the variable resolution and speed. The MA735 is probably one of the cheapest Mag Alpha sensors out there.
1 parent bfd07bd commit 07fbcc9

File tree

7 files changed

+558
-0
lines changed

7 files changed

+558
-0
lines changed

‎src/encoders/ma735/MA735.cpp‎

Lines changed: 297 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,297 @@
1+
#include "MA735.h"
2+
3+
MA735::MA735(SPISettings settings, int nCS) : settings(settings), nCS(nCS) {
4+
5+
};
6+
MA735::~MA735() {
7+
8+
};
9+
10+
void MA735::init(SPIClass* _spi) {
11+
spi = _spi;
12+
if (nCS >= 0) {
13+
pinMode(nCS, OUTPUT);
14+
digitalWrite(nCS, HIGH);
15+
}
16+
};
17+
18+
float MA735::getCurrentAngle() {
19+
return (readRawAngle() * _2PI)/MA735_16BIT;//It doesn't matter that it is divided by 65536, because the raw angle fills empty data bits with empty zeros so sensor resolution doesn't affect angle calculation
20+
}; // angle in radians, return current value
21+
22+
uint16_t MA735::readRawAngle() {
23+
uint16_t angle = transfer16(0x0000);
24+
return angle;
25+
}; // 9-13bit angle value
26+
27+
uint16_t MA735::getZero() {
28+
uint16_t result = readRegister(MA735_REG_ZERO_POSITION_MSB)<<8;
29+
result |= readRegister(MA735_REG_ZERO_POSITION_LSB);
30+
return result;
31+
};
32+
uint8_t MA735::getBiasCurrentTrimming() {
33+
return readRegister(MA735_REG_BCT);
34+
};
35+
bool MA735::isBiasCurrrentTrimmingX() {
36+
return (readRegister(MA735_REG_ET) & 0x01)==0x01;
37+
};
38+
bool MA735::isBiasCurrrentTrimmingY() {
39+
return (readRegister(MA735_REG_ET) & 0x02)==0x02;
40+
};
41+
uint16_t MA735::getPulsesPerTurn() {
42+
uint16_t result = readRegister(MA735_REG_ILIP_PPT_LSB)>>6;
43+
result |= ((uint16_t)readRegister(MA735_REG_PPT_MSB))<<2;
44+
return result+1;
45+
};
46+
uint8_t MA735::getIndexLength() {
47+
return (readRegister(MA735_REG_ILIP_PPT_LSB)>>2)&0x0F;
48+
};
49+
uint8_t MA735::getRotationDirection() {
50+
return (readRegister(MA735_REG_RD)>>7);
51+
};
52+
uint8_t MA735::getFieldStrengthHighThreshold() {
53+
return (readRegister(MA735_REG_MGLT_MGHT)>>2)&0x07;
54+
};
55+
uint8_t MA735::getFieldStrengthLowThreshold() {
56+
return (readRegister(MA735_REG_MGLT_MGHT)>>5)&0x07;
57+
};
58+
FieldStrength MA735::getFieldStrength() {
59+
return (FieldStrength)(readRegister(MA735_REG_MGH_MGL)>>6);
60+
};
61+
uint8_t MA735::getFilterWindow() {
62+
return readRegister(MA735_REG_FW);
63+
};
64+
uint8_t MA735::getHysteresis() {
65+
return readRegister(MA735_REG_HYS);
66+
};
67+
float MA735::getResolution() {
68+
//All I could find in the datasheet was a table with the correlation, no function to convert Filter window to res.
69+
uint8_t reg = readRegister(MA735_REG_FW);
70+
float result;
71+
switch (reg) {
72+
case 51:
73+
result = 9.0;
74+
break;
75+
case 68:
76+
result = 9.5;
77+
break;
78+
case 85:
79+
result = 10.0;
80+
break;
81+
case 102:
82+
result = 10.5;
83+
break;
84+
case 119:
85+
result = 11.0;
86+
break;
87+
case 136:
88+
result = 11.5;
89+
break;
90+
case 153:
91+
result = 12.0;
92+
break;
93+
case 170:
94+
result = 12.5;
95+
break;
96+
case 187:
97+
result = 13.0;
98+
break;
99+
default:
100+
result = 11.0;
101+
break;
102+
}
103+
return result;
104+
};
105+
int MA735::getUpdateTime() {
106+
//All I could find in the datasheet was a table with the correlation, no function to convert Filter window to update time.
107+
//Returns result in microseconds
108+
uint8_t reg = readRegister(MA735_REG_FW);
109+
int result;
110+
switch (reg) {
111+
case 51:
112+
result = 64;
113+
break;
114+
case 68:
115+
result = 128;
116+
break;
117+
case 85:
118+
result = 256;
119+
break;
120+
case 102:
121+
result = 512;
122+
break;
123+
case 119:
124+
result = 1024;
125+
break;
126+
case 136:
127+
result = 2048;
128+
break;
129+
case 153:
130+
result = 4096;
131+
break;
132+
case 170:
133+
result = 8192;
134+
break;
135+
case 187:
136+
result = 16384;
137+
break;
138+
default:
139+
result = 1024;
140+
break;
141+
}
142+
return result;
143+
};
144+
145+
146+
147+
void MA735::setZero(uint16_t value) {
148+
writeRegister(MA735_REG_ZERO_POSITION_MSB, value>>8);
149+
writeRegister(MA735_REG_ZERO_POSITION_LSB, value&0x00FF);
150+
};
151+
void MA735::setBiasCurrentTrimming(uint8_t value) {
152+
writeRegister(MA735_REG_BCT, value);
153+
};
154+
void MA735::setBiasCurrrentTrimmingEnabled(bool Xenabled, bool Yenabled) {
155+
uint8_t val = Xenabled ? 0x01 : 0x00;
156+
val |= (Yenabled ? 0x02 : 0x00);
157+
writeRegister(MA735_REG_ET, val);
158+
};
159+
void MA735::setPulsesPerTurn(uint16_t value) {
160+
uint16_t pptVal = value - 1;
161+
writeRegister(MA735_REG_PPT_MSB, pptVal>>2);
162+
uint8_t val = readRegister(MA735_REG_ILIP_PPT_LSB);
163+
val &= 0x3F;
164+
val |= (pptVal&0x03)<<6;
165+
writeRegister(MA735_REG_ILIP_PPT_LSB, val);
166+
};
167+
void MA735::setIndexLength(uint8_t value) {
168+
uint8_t val = readRegister(MA735_REG_ILIP_PPT_LSB);
169+
val &= 0xC0;
170+
val |= ((value<<2)&0x3F);
171+
writeRegister(MA735_REG_ILIP_PPT_LSB, val);
172+
};
173+
void MA735::setRotationDirection(uint8_t value) {
174+
if (value==0)
175+
writeRegister(MA735_REG_RD, 0x00);
176+
else
177+
writeRegister(MA735_REG_RD, 0x80);
178+
};
179+
void MA735::setFieldStrengthThresholds(uint8_t high, uint8_t low) {
180+
uint8_t val = (low<<5) | (high<<2);
181+
writeRegister(MA735_REG_MGLT_MGHT, val);
182+
};
183+
void MA735::setFilterWindow(uint8_t value) {
184+
writeRegister(MA735_REG_FW, value);
185+
};
186+
void MA735::setHysteresis(uint8_t value) {
187+
writeRegister(MA735_REG_HYS, value);
188+
};
189+
void MA735::setResolution(float res) {
190+
//All I could find in the datasheet was a table with the correlation, no function to convert Filter window to res.
191+
uint8_t value;
192+
uint8_t res_int = res * 10;//It has to be a basic type for the switch case
193+
switch (res_int) {
194+
case 90:
195+
value = 51;
196+
break;
197+
case 95:
198+
value = 68;
199+
break;
200+
case 100:
201+
value = 85;
202+
break;
203+
case 105:
204+
value = 102;
205+
break;
206+
case 110:
207+
value = 119;
208+
break;
209+
case 115:
210+
value = 136;
211+
break;
212+
case 120:
213+
value = 153;
214+
break;
215+
case 125:
216+
value = 170;
217+
break;
218+
case 130:
219+
value = 187;
220+
break;
221+
default:
222+
value = 119;
223+
break;
224+
}
225+
writeRegister(MA735_REG_FW, value);
226+
};
227+
void MA735::setUpdateTime(int microsec) {
228+
//All I could find in the datasheet was a table with the correlation, no function to convert Filter window to update time.
229+
//time in microseconds
230+
uint8_t value;
231+
switch (microsec) {
232+
case 64:
233+
value = 51;
234+
break;
235+
case 128:
236+
value = 68;
237+
break;
238+
case 256:
239+
value = 85;
240+
break;
241+
case 512:
242+
value = 102;
243+
break;
244+
case 1024:
245+
value = 119;
246+
break;
247+
case 2048:
248+
value = 136;
249+
break;
250+
case 4096:
251+
value = 153;
252+
break;
253+
case 8192:
254+
value = 170;
255+
break;
256+
case 16384:
257+
value = 187;
258+
break;
259+
default:
260+
value = 119;
261+
break;
262+
}
263+
writeRegister(MA735_REG_FW, value);
264+
};
265+
266+
267+
uint16_t MA735::transfer16(uint16_t outValue) {
268+
spi->beginTransaction(settings);
269+
if (nCS >= 0)
270+
digitalWrite(nCS, LOW);
271+
uint16_t value = spi->transfer16(outValue);
272+
if (nCS >= 0)
273+
digitalWrite(nCS, HIGH);
274+
spi->endTransaction();
275+
return value;
276+
};
277+
uint8_t MA735::readRegister(uint8_t reg) {
278+
uint16_t cmd = 0x4000 | ((reg&0x001F)<<8);
279+
uint16_t value = transfer16(cmd);
280+
delayMicroseconds(1);
281+
value = transfer16(0x0000);
282+
return value>>8;
283+
};
284+
uint8_t MA735::writeRegister(uint8_t reg, uint8_t value) {
285+
uint8_t write_check = readRegister(reg);
286+
//no need to rewrite, it is the exact same value
287+
if (write_check == value) {
288+
return write_check;
289+
}
290+
else {
291+
uint16_t cmd = 0x8000 | ((reg&0x1F)<<8) | value;
292+
uint16_t result = transfer16(cmd);
293+
delay(20); // 20ms delay required
294+
result = transfer16(0x0000);
295+
return result>>8;
296+
}
297+
};

‎src/encoders/ma735/MA735.h‎

Lines changed: 87 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,87 @@
1+
#ifndef __MA735_H__
2+
#define __MA735_H__
3+
4+
5+
#include "Arduino.h"
6+
#include "SPI.h"
7+
8+
enum FieldStrength : uint8_t {
9+
FS_NORMAL = 0x00,
10+
FS_LOW = 0x01,
11+
FS_HIGH = 0x02,
12+
FS_ERR = 0x03 // impossible state
13+
};
14+
15+
16+
#define _2PI 6.28318530718f
17+
#define MA735_16BIT 65536.0f
18+
19+
#define MA735_REG_ZERO_POSITION_LSB 0x00
20+
#define MA735_REG_ZERO_POSITION_MSB 0x01
21+
#define MA735_REG_BCT 0x02
22+
#define MA735_REG_ET 0x03
23+
#define MA735_REG_ILIP_PPT_LSB 0x04
24+
#define MA735_REG_PPT_MSB 0x05
25+
#define MA735_REG_MGLT_MGHT 0x06
26+
#define MA735_REG_RD 0x09
27+
#define MA735_REG_FW 0x0E
28+
#define MA735_REG_HYS 0x10
29+
#define MA735_REG_MGH_MGL 0x1B
30+
31+
#define MA735_BITORDER MSBFIRST
32+
33+
static SPISettings MA735SPISettings(1000000, MA735_BITORDER, SPI_MODE3); // @suppress("Invalid arguments")
34+
static SPISettings MA735SSISettings(4000000, MA735_BITORDER, SPI_MODE1); // @suppress("Invalid arguments")
35+
36+
37+
class MA735 {
38+
public:
39+
MA735(SPISettings settings = MA735SPISettings, int nCS = -1);
40+
virtual ~MA735();
41+
42+
virtual void init(SPIClass* _spi = &SPI);
43+
44+
float getCurrentAngle(); // angle in radians, return current value
45+
46+
uint16_t readRawAngle(); // 9-13bit angle value
47+
uint16_t readRawAngleSSI(); // 9-13bit angle value
48+
49+
uint16_t getZero();
50+
uint8_t getBiasCurrentTrimming();
51+
bool isBiasCurrrentTrimmingX();
52+
bool isBiasCurrrentTrimmingY();
53+
uint16_t getPulsesPerTurn();
54+
uint8_t getIndexLength();
55+
uint8_t getRotationDirection();
56+
uint8_t getFieldStrengthHighThreshold();
57+
uint8_t getFieldStrengthLowThreshold();
58+
FieldStrength getFieldStrength();
59+
uint8_t getFilterWindow();
60+
uint8_t getHysteresis();
61+
float getResolution();
62+
int getUpdateTime();
63+
64+
void setZero(uint16_t);
65+
void setBiasCurrentTrimming(uint8_t);
66+
void setBiasCurrrentTrimmingEnabled(bool Xenabled, bool Yenabled);
67+
void setPulsesPerTurn(uint16_t);
68+
void setIndexLength(uint8_t);
69+
void setRotationDirection(uint8_t);
70+
void setFieldStrengthThresholds(uint8_t high, uint8_t low);
71+
void setFilterWindow(uint8_t);
72+
void setHysteresis(uint8_t);
73+
void setResolution(float resolution);
74+
void setUpdateTime(int microsec);
75+
76+
private:
77+
SPIClass* spi;
78+
SPISettings settings;
79+
int nCS = -1;
80+
//float MA735_CPR = 65536.0f;
81+
82+
uint16_t transfer16(uint16_t outValue);
83+
uint8_t readRegister(uint8_t reg);
84+
uint8_t writeRegister(uint8_t reg, uint8_t value);
85+
};
86+
87+
#endif

0 commit comments

Comments
 (0)