Guru Meditation Error: Cache disabled but cached memory region accessed

[raduangelescu]

Hello,

I have piece of code that after running a few hours (3-5 hours) gives me the above kernel panic "Guru Meditation Error: Cache disabled but cached memory region accessed" . The callstack does not tell me anything (it doesn't dump much).

This is the culprit code (if I remove digitalWrite from timer ISR it no longer crashes, but that could be because the whole code gets optimized and doesn't execute).

Code: [Select all] [Expand/Collapse]

1. #pragma once
2.  
3. #include <Settings.h>
4.  
5. DRAM_ATTR volatile unsigned long long inctimer = 0;
6. DRAM_ATTR volatile bool onlyLow = false;
7. DRAM_ATTR volatile unsigned char g_state = 0;
8. DRAM_ATTR volatile const unsigned long long divizor = 10;
9. DRAM_ATTR volatile unsigned long  startZCMicros = 0;
10. DRAM_ATTR volatile unsigned long long intervalZCMicros = 10000/divizor; // 50 hz
11. DRAM_ATTR volatile unsigned long long pulseLengthMicros = 300/divizor;
12. DRAM_ATTR volatile unsigned long long pulseBeginMicros  = LONG_MAX;
13. DRAM_ATTR volatile unsigned long  long pulseOffsetZCMicros = LONG_MAX;
14.  
15. void IRAM_ATTR OnTimerHeater()
16. {
17.     if(onlyLow)
18.     {
19.         digitalWrite(CONTROL_PIN, LOW);
20.         return;
21.     }
22.     volatile long currentMicros = micros()/divizor;
23.     volatile long localPulseBeginMicros = pulseBeginMicros + pulseOffsetZCMicros;
24.     volatile long localPulseEndMicros   = pulseBeginMicros + pulseOffsetZCMicros + pulseLengthMicros;
25.    
26.     if(currentMicros >= localPulseEndMicros)
27.     {
28.          digitalWrite(CONTROL_PIN, LOW);
29.     }
30.     else if(currentMicros  >= localPulseBeginMicros)
31.     {
32.          digitalWrite(CONTROL_PIN, HIGH);
33.     }
34.  
35. }
36.  
37. void IRAM_ATTR OnZeroCrossHeater()
38. {
39.     volatile const long current_micros = micros()/divizor;
40.     volatile int i = 0;
41.     if(digitalRead(ZERO_CROSS_PIN) == LOW)
42.     {
43.         for (; i < 1000; ++i) {}
44.         if(digitalRead(ZERO_CROSS_PIN) == HIGH)
45.         {
46.             return;
47.         }
48.     }
49.     else
50.     {
51.         return;
52.     }
53.  
54.     if(current_micros - startZCMicros < 100)
55.     {
56.         return;
57.     }
58.  
59.  
60.     switch(g_state)
61.     {
62.         case 0:
63.             startZCMicros = current_micros;
64.             break;
65.         case 1:
66.             intervalZCMicros = current_micros - startZCMicros;
67.             break;    
68.     }
69.  
70.     g_state++;
71.     if(g_state > 1)
72.     {
73.         g_state = 0;
74.     }
75.  
76.     if(intervalZCMicros != -1)
77.     {
78.         pulseBeginMicros = current_micros;
79.     }
80. }
81.  
82. class Heater
83. {
84.     double      m_prev_value  = 0.0;
85.     hw_timer_t* m_timer  = nullptr;
86.  
87.     public:
88.  
89.     Heater()
90.     {
91.  
92.     }
93.  
94.     void setup()
95.     {
96.         pinMode(CONTROL_PIN, OUTPUT);
97.         pinMode(ZERO_CROSS_PIN, INPUT_PULLUP);
98.  
99.         digitalWrite(CONTROL_PIN, LOW);
100.  
101.         m_timer = timerBegin(0, 80 * divizor, true);
102.         // per microsecond
103.         timerAttachInterrupt(m_timer, &OnTimerHeater, true);
104.         timerAlarmWrite(m_timer, 1, true);
105.  
106.         timerAlarmEnable(m_timer);
107.  
108.         attachInterrupt(ZERO_CROSS_PIN, OnZeroCrossHeater, RISING);
109.     }
110.    
111.     void set(double value)
112.     {
113.         if(value > 50.0)
114.         {
115.             value = 50.0;
116.         }
117.         if(value < 0.0)
118.         {
119.             value = 0.0;
120.         }
121.        
122.         unsigned long long localinterval = intervalZCMicros;
123.      
124.         if(m_prev_value == value)
125.         {
126.             return;
127.         }
128.      
129.         unsigned long long localCalculation = 0;
130.         if(abs(value) < 0.01 )
131.         {
132.             localCalculation = LONG_MAX;
133.             onlyLow = true;
134.         }
135.         else
136.         {
137.             onlyLow = false;
138.             localCalculation = (long long)((100.0 - value) * 0.01 * localinterval) - pulseLengthMicros;
139.         }
140.        
141.         if(localCalculation < 0)
142.         {
143.             localCalculation = 0;
144.         }
145.  
146.      
147.         pulseOffsetZCMicros = localCalculation;
148.        
149.        
150.         Serial.print("heating with ");
151.         Serial.print(value);
152.      
153.         Serial.println("--");
154.         m_prev_value = value;
155.     }
156.  
157.     void loop()
158.     {
159.     }
160. };

GeSHi © Codebox Plus Extension

I researched the problem but I can't understand what is the cache that is accessed.. I made everything volatile and in DRAM... (I don't use SPI , only I2C)

Cheers,
Radu

[raduangelescu]

As a memory "dump" I only get : Memory dump at 0x40161aec: bad00bad bad00bad bad00bad

[ESP_Sprite]

This happens if you call a function that is not in IRAM (perhaps digitalWrite?) while the flash cache is disabled because the ESP32 needs to write to flash. However, normally ESP-IDF disables interrupts when it accesses flash unless you specifically tell it not to... I don't know if the Arduino code also does this, though.

[ningappa BS]

This happens if you call a function that is not in IRAM (perhaps digitalWrite?) while the flash cache is disabled because the ESP32 needs to write to flash. However, normally ESP-IDF disables interrupts when it accesses flash unless you specifically tell it not to... I don't know if the Arduino code also does this, though.

Hi ESP_Sprite,

I used GPIO.out_w1tc = (1 << 19) instred of gpio_set_level(GPIO_NUM_19, 0) but still I'm getting error Guru Meditation Error: Cache disabled but cached memory region accessed and I did not get SPI_MASTER_ISR_IN_IRAM in menuconfig and also in sdkconfig. Please help me to solve problem.

thanks