CN101751303B - Watchdog system in embedded device and control method thereof - Google Patents
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Abstract
The invention discloses a watchdog system in an embedded device and a control method thereof. The control method comprises the following steps: shielding the watchdog when a shielding condition is met and starting the watchdog when a starting condition is met, wherein the shielding condition comprises: the power-on confirmation code received from the embedded device is the same with that preset in the watchdog after the watchdog is powered on or reset. The system comprises a counter, a power-on initial value register, a power-on confirmation code register and a starting code register; and a logic discriminating module is used for shielding the counter and assigning a shielding value to the power-on initial value register when the value of the power-on initial value register is an initial value and the value of the power-on confirmation code register is the preset power-on confirmation code. In the invention, the watchdog is shielded only if the watchdog is powered on or reset, and therefore the watchdog can not be shielded until the watchdog is energized again after being deenergized, thereby improving the stability of the watchdog and the security of the embedded device.
Description
Technical field
The present invention relates to watchdog technique, watchdog system and control method thereof in particular a kind of embedded device.
Background technology
Watchdog circuit mainly is the state of supervisory system, when system because when situation such as deadlock appears in reason in certain, the resetting of watchdog circuit triggering system.The system that makes can restart, and from collapse, recovers.Present watchdog circuit generally is to 8 design of singlechip system, is divided into having to enable to import and do not have enabling to import: do not enable to import, one powers on, and watchdog circuit just triggers; Be generally used for 8 SCM system,, can enable input, once the work of powering on because 8 SCM system is fairly simple.But for 32,64 high-end embedded device, because the reason of embedded device is housed, general start-up time is all long, has about 30 seconds.For so high-end embedded device; At the initial stage that powers on, can not trigger house dog, could start house dog after waiting embedded device to start fully to finish; The watchdog circuit that does not enable to import just can not directly be used in the high-end embedded device, and this just requires house dog to enable input; But there is the input of enabling to mean to have that the chance that does not enable (conductively-closed) is arranged equally; Because enabling input generally is to be controlled by CPU itself; But the state that enables output itself of the cpu system of collapse is uncertain, is easy to shield house dog, and house dog cannot be worked; The stability of house dog work has also reduced the security of embedded device inadequately.
Therefore, prior art awaits to improve and development.
Summary of the invention
The object of the present invention is to provide watchdog system and control method thereof in a kind of embedded device, adopt this system and method can improve the stability of house dog work and the security of embedded device.
Technical scheme of the present invention is following:
The control method of house dog in a kind of embedded device shields said house dog when satisfying the shielding condition, when satisfying entry condition it is started, and said shielding condition comprises: after said house dog powers on or resets; The affirmation coding that powers on that the affirmation that powers on is encoded and said house dog is preset that receives from said embedded device is identical.
Described method, wherein, said shielding condition comprises: said house dog, receives said powering on from said embedded device and confirms coding in the cycle in a preset level signal.
Described method wherein, when shielding said house dog, is given masking value with the initial registers assignment that powers on of said house dog.
Described method, wherein, said entry condition comprises: said house dog is received the enabled instruction of being sent by said embedded device under masked state, and starts said house dog according to this enabled instruction.
Described method, wherein, said house dog is given the startup value with the said initial registers assignment that powers on after starting according to enabled instruction.
Described method, wherein, said entry condition comprises: when the initial registers that powers on of said house dog is not endowed masking value, start said house dog.
The present invention also provides the watchdog system in a kind of embedded device, comprising: counter, the initial registers that powers on, powering on of being connected with said embedded device are confirmed code registers and are started code registers; Also comprise: differentiate logic module, be used for value in the said initial registers that powers on and be initial value and the value of confirming code registers of powering on when confirming coding, shield said counter and compose masking value for the said initial registers that powers on for preset powering on.
Described system wherein, also comprises: with the last power detection circuit that said differentiation logic module is connected, be used for level signal with a predetermined period and trigger said differentiation logic module and confirm that from said powering on code registers reads coding.
Described system wherein, when the value that said differentiation logic module is composed masking value and said startup code registers in the said initial registers that powers on is the startup coding of presetting, starts said counter.
Described system, wherein, said differentiation logic module directly starts said counter when the said initial registers that powers on is not composed masking value.
Described system wherein, also comprises: be connected in said embedded device and power on and confirm code registers and start the serial-parallel conversion circuit between the code registers.
Described system wherein, also comprises: the frequency division that is connected between said serial-parallel conversion circuit and the counter is provided with register, is used for trigger interval cycle of said storage watchdog system.
The control method of house dog in the embedded device provided by the present invention must satisfy following two conditions as shielding house dog: at first will satisfy behind the house dog electrification reset simultaneously; To confirm that also the instruction that house dog receives meets the upper electric shielding condition that is provided with in advance; Make that in this condition behind the house dog electrification reset house dog only again could conductively-closed after the energising in outage again; House dog is in case work like this; Even the state labile that enables to export after the collapse of monitored equipment; House dog can not improved the stability of house dog work and the security of embedded device by shielding all of a sudden yet.
Description of drawings
Fig. 1 is the schematic block diagram of house dog and embedded device in the watchdog system of the present invention;
Fig. 2 is the circuit block diagram of house dog in the watchdog system of the present invention;
Fig. 3 goes up power detection circuit, house dog register and receives to power on to confirm the sequential chart of the coding and the initialize that whether powers in the watchdog system of the present invention;
Fig. 4 is the process flow diagram of watchdog system control method of the present invention.
Embodiment
Watchdog system in the embedded device of this embodiment, whole concrete application circuit is as shown in Figure 1, and embedded device passes through serial data line s_data, s_clk transmission order and data to watchdog circuit; Through the wd_reset watchdog circuit (promptly feeding dog) that periodically resets, in case the embedded device collapse, watchdog circuit is not received the wd_reset signal in official hour simultaneously, and watchdog circuit is just exported the embedded device that resets through reset; The clk signal is an external timing signal, is used for the inner rolling counters forward of watchdog circuit regularly.
The house dog internal circuit is as shown in Figure 2, and house dog can use common logical circuit to form, or builds with logical circuits such as CPLD, FPGA, ASIC.
House dog mainly comprises: the serial-parallel conversion circuit 910 that is connected with embedded device through serial data line s_data, s_clk; Receive external timing signal clk and embedded device feeding-dog signal wd_reset and export the counter 940 of reset signal reset; The differentiation logic module 930 that is connected with counter 940; With differentiate last power detection circuit 920 that logic module 930 is connected, initial registers 951 powers on; Be separately positioned on powering on affirmation code registers 952, the startup code registers 953 differentiated between logic module 930 and the serial-parallel conversion circuit 910; The frequency division that is arranged between counter 940 and the serial-parallel conversion circuit 910 is provided with register 954.
Said counter 940 is connected with the initial registers 951 that powers on, the affirmation code registers 952 that powers on, startup code registers 953 respectively, and the initial registers 951 that when sending reset signal reset, will power on, the affirmation code registers 952 that powers on and startup code registers 953 are changed to 0.
Said differentiation logic module 930 is connected with the said initial registers 951 that powers on; Being used at the initial value that powers on is 0 and when powering on of receiving of said embedded device confirmed to be encoded to preset coding, shields said counter 940, and composes masking values for the initial registers 951 that powers on.
Whether the initial value that powers on is to be used for inspection to be in and to have powered on or after the watchdog reset system restarts, whether triggered the state of house dog, in this embodiment, if just power on or reset, composes a masking value 0x5a for the initial registers that powers on; In case house dog is triggered, this initial value that powers on is modified and is startup value 0xa5, and this is the eliminating coding of the interference that possibly occur system, comes the enhanced system antijamming capability with it.Powering on and confirming that coding is that to be used for the affirmation system be when just having powered on now really, like 0xaa.Start coding and be used for starting watchdog circuit, like 0x5aa5.
After the initial registers that powers on 951 is composed masking value; House dog is with regard to conductively-closed; Differentiate logic module 930 and only receive that start behind the coding 0x5aa5 could enabling counting device 940; Differentiate logic module 930 this moment and compose a startup value oxa5 for the initial registers that powers on, house dog work in a single day like this is even occurred in the system disturbing; To detect value in the initial registers that powers on be that 0xa5 just can screen-wall counter 940 as long as differentiate logic module 930, improved the stability of house dog work and the security of embedded device.
Last power detection circuit 920 with differentiate logic module 930 and be connected, be used for level signal with a predetermined period and trigger said differentiation logic module 930 and read coding from the said affirmation code registers that powers on; Last power detection circuit 920 can wait with the R-C circuit and realize, if house dog realizes that with ASIC this circuit can be made in the chip, if will be placed on outside the chip with CPLD, this circuit of FPGA.Power detection circuit 920 these authentication conditions can further reduce the influence of external interference in the increase, improve the stability of system.
The level signal that said differentiation logic module 930 produces at last power detection circuit 920 does not receive in the cycle to power on and can not compose masking value for the initial registers that powers on when confirming coding that said counter 940 is directly started working.Can avoid said house dog not start like this because of being interfered.
The effect of serial-parallel conversion circuit 910 is antijamming capabilities of enhanced system; If with the words of serial input; When being interfered, occur that the probability of preset value still exists, but after going here and there and change with serial-parallel conversion circuit 910; Probability is almost nil, and this is the stability of elevator system significantly.
Frequency division is provided with the trigger interval cycle (watchdogtimeout period) that register 954 is used for storing watchdog circuit.
The concrete course of work of native system is following:
After start powered on, last power detection circuit 920 output one-periods were the low level signal of 500ms, and in the preceding 10ms of this 500ms, the differentiation logic module 930 following register that resets: the initial registers that powers on 951 is changed to 0; Power on and confirm that code registers 952 is reset to 0; Start code registers 953 and be reset to 0.
Arrive 450ms during this period of time at 10ms, embedded device is through s_data, and one of s_clk transmission powers on and confirms coding (like 0xaa) to house dog, and this powers on and confirms that code storage is in the affirmation code registers 952 that powers on.
At 450ms between the 500ms; Differentiating logic module 930 confirm the to power on initial value of initial registers 951 storages is 0 and is stored in to power on and confirms that powering in the code registers 952 confirm to be encoded under the situation of 0xaa; Compose masking value for the initial registers 951 that powers on; Assignment is 0x5a, otherwise assignment not.
Like this, behind the 500ms that powers on, after the initial registers that powers on 951 was assigned masking value, the house dog conductively-closed can not worked.
After embedded device was accomplished whole startup work through one long period, through s_data, s_clk sent a startup coding (as being 0x5aa5) and gives house dog, is stored in said startup code registers 953.
Said differentiation logic module 930 reads said startup coding, if judging to start is encoded to 0x5aa5, and the initial value that powers on sends enabling signal enabling counting device 940 when being 0x5a, and the initial registers 951 that will power on simultaneously is changed to startup value 0xa5; Power on and confirm that code registers 952 is reset to 0; Start code registers 953 and be reset to 0.
Last power detection circuit 920, read to power on and confirm code registers 952 and the assignment of the initial registers 951 that powers on; Certain relation is arranged: like Fig. 3 on control timing; Only when last power detection circuit 920 is output as low (showing it is just to power on); Power on and confirm that the input of encoding is just effective, otherwise input is illegal, does not receive.The initial value that powers on also is whether on during this period of time, to differentiate assignment, otherwise does not do new assignment work.This also is the effect that strengthens antijamming capability.Certainly, when system crash and after by watchdog reset, whole process does not re-power, and system is with reset output signal come to power on the synchronously input of confirming coding and the assignment of the initial value that powers on.Through the enable mechanism of above multiple authentication, make no matter what the entire circuit system received to disturb that house dog can both make the system restart of collapse.
With reference to figure 4, the present invention also provides the control method of house dog in a kind of embedded device, and wherein the upper electric shielding process of house dog is following:
101, start powers on;
102, go up the low level signal of a predetermined period of power detection circuit 920 outputs, this embodiment adopts 500ms;
103, in preceding 10ms, reset oneself register of house dog self: the initial registers that will power on 951 is changed to 0; Power on and confirm that code registers 952 is reset to 0; Start code registers 953 and be reset to 0;
104,10ms to 450ms during this period of time, embedded device is through s_data, s_clk sends one to house dog and powers on and confirm coding, preset powering on confirms that coding is 0xaa in this embodiment;
105, to 500ms during this period of time, the house dog initial value of confirming to power on has been changed to 0 and power on and confirm to be encoded under the situation of 0xaa, composes masking value 0x5a for the initial registers 951 that powers on of house dog at 450ms;
106, behind the 500ms,, the house dog conductively-closed, do not start if the initial registers 951 of powering on is composed masking value 0x5a.
After embedded device was accomplished whole startup work through one long period, through s_data, s_clk sent a startup coding and gives house dog as enabled instruction, and the preset startup in this embodiment is encoded to 0x5aa5; The start-up course of house dog is following:
201, house dog judges whether the initial registers 951 that powers on is masking value 0x5a; Be then to carry out 202, otherwise carry out 203; The purpose of jump procedure 203 is can not be activated in order to prevent house dog to be interfered always in this step.
202, house dog judges whether the startup coding of receiving is the preset coding 0x5aa5 that starts, and is then to carry out 203; Otherwise this step is carried out in circulation;
203, the counter 940 of house dog is activated, and house dog is started working;
204, the following register of watchdog circuit set/reset: the initial registers that powers on 951 is changed to startup value 0xa5; Power on and confirm that code registers 952 is reset to 0; Start code registers 953 and be reset to 0; The counter of house dog begins counting;
The condition that starts house dog under the normal condition is: the initial value that powers on is that the startup of masking value 0x5a and input is encoded to 0x5aa5.Can not be activated for preventing that house dog is interfered always, when the initial value that powers on is not masking value 0x5a, also can directly not start.
In the process of system's operation, undertaken by following flow process:
If 301 house dogs in the cycle, have been received the feeding-dog signal wd_reset of embedded device at trigger interval, then carry out 302; And when system crash do not go in time to feed dog and cause reset after, house dog is simulated the last power detection circuit 920 that produces 500ms simultaneously and exports signals, following register simultaneously resets: the initial registers that powers on 951 set are 0; Power on and confirm that code registers 952 is reset to 0; Start code registers 953 and be reset to 0; System came back to for the 103rd step like this, recommunicate with the equipment of restarting.
302, the house dog counter that resets is 0;
303, whether the power on value of initial registers 951 is 0xa5; Then be judged as error condition if yes, house dog is disturbed, and does not process; If otherwise carry out 203; The purpose of jump procedure 203 is in order to prevent that house dog was interfered because of the initial registers 951 that powers in when work in this step, makes house dog conductively-closed in should not conductively-closed.
In the process of system's operation, confirm coding if the embedded device mistake has been imported to power on, and by chance confirm coding 0xaa, but, power on and confirm that code registers 952 can be by assignment because there is not to satisfy the low level signal of a 500ms for preset powering on.Confirm coding if the embedded device mistake has by chance been imported for 0xaa powers on, and the last power detection circuit 920 of simultaneity factor is interfered simultaneously and exports the low level signal greater than 500ms, cause powering on and confirm that code registers 952 is by assignment; But as long as the value of the initial registers 951 that powers on is not 0, the initial registers that powers on 951 just can not given masking value 0x5a.
As long as house dog enables control, this enables to be interfered and makes mistakes, and can occur the state of " error condition; house dog is disturbed " among the figure, and this is to have received the situation that extraneous very big strong jammings such as electromagnetism just possibly occur in entire circuit, if under strong jamming; The probability that arbitrary position of inner any one register is changed to " 1 " is 1%; The probability that is changed to " 0 " is 99%, and so, the initial registers that powers on 951 by interference for the probability of 0x5a is:
1％×99％×1％×99％×1％×99％×1％×99％
That is to say, received under the extraneous very big strongly disturbing situation such as electromagnetism that have an appointment 1/100000000th probability of house dog is not worked in entire circuit.
Be the verilog code that decision logic module 930 realizes differentiating logic below:
Reg start_up_detect//go up power detection circuit 920 to export.
Init_code//Reg [7:0] powers on initial value
Reg [7:0] start_confirm_code//power on and confirm coding
Reg [15:0] start_code // startup coding
Reg start_count // enabling signal
Reg wd_reset_out; The output of // watchdog reset.
Reg?wd_reset_out_d1；
Reg?selfreset_flag；
Reg[7:0]wd_selfreset_count；
Wd_reset_out_d1＜＝wd_reset_out；
If((reset_out_d1＝＝0)&&(reset_out＝＝1))
Begin
Selfreset_flag＜＝1；
End
If((selfreset_flag＝＝1)&&(wd_selfreset_count＜0xf1))
wd_selfreset_count++；
If(((start_up_detect＝＝0)||((wd_selfreset_count＞0)&&(wd_selfrest_count＜0
xf0)))&&(start_confirm_code＝＝0xaa)&&(init_code＝＝0x00))init_code＜＝0x5a；
Else?init_code＜＝init_code；
If(start_up_detect＝＝1)
Begin
If(((init_code＝＝0x5a)&&(start_code＝＝0x5aa5))||(init_code！＝0x5a)
Begin
Start_count＜＝1；
Init_code＜＝0xa5；
start_confirm_code＜＝0；
start_code＜＝0；
End
Else
Begin
Start_count＜＝0；
Init_code＜＝init_code；
start_confirm_code＜＝0；
start_code＜＝0；
end
End
Be the verilog code of realizing counter 940 outputs below:
Reg [15:0] wd_period; The trigger interval cycle of // watchdog circuit
Reg [15:0] wd_count; // house dog counter 940
Reg wd_reset; The input of // watchdog reset.
Reg?wd_reset_d1；
Reg?wd_reset_d2；
Wd_reset_d1＜＝wd_reset；
Wd_reset_d2＜＝wd_reset_d1；
If(start_count＝＝1)
Begin
Wd_count＜＝wd_count+1；
If((wd_d2＝＝1)&&(wd_d1＝＝0))wd_count＜＝0；
End
Else
Wd_count＜＝0；
If(wd_count＝＝wd_period)wd_reset_out＜＝0；
Else_wd_reset_out＜＝1；
When system crash and after, show that total system has received certain and disturbed all values in the previous operation of house dog that at this moment need reset by watchdog reset.Total system can reconfigure.Mainly be the initial registers 951 that powers on that resets, power on and confirm code registers 952 to start code registers 953.The realization code is following:
If((reset_out_d1＝＝0)&&(reset_out＝＝1))
Begin
init_code＜＝0；
start_confirm_code＜＝0；
start_code＜＝0；
End
Should be understood that application of the present invention is not limited to above-mentioned giving an example, concerning those of ordinary skills, can improve or conversion that all these improvement and conversion all should belong to the protection domain of accompanying claims of the present invention according to above-mentioned explanation.
Claims (12)
1. the control method of house dog in the embedded device shields said house dog when satisfying the shielding condition, when satisfying entry condition it is started, and it is characterized in that said shielding condition comprises:
After said house dog powers on or sends reset signal;
The affirmation coding that powers on that the affirmation that powers on is encoded and said house dog is preset that receives from said embedded device is identical.
2. method according to claim 1 is characterized in that, said shielding condition comprises: said house dog, receives said powering on from said embedded device and confirms coding in the cycle in a preset level signal.
3. method according to claim 1 and 2 is characterized in that, when shielding said house dog, masking value is given the initial registers that powers on of said house dog.
4. method according to claim 3 is characterized in that, said entry condition comprises: said house dog is received the enabled instruction of being sent by said embedded device under masked state, and starts said house dog according to this enabled instruction.
5. method according to claim 4 is characterized in that, said house dog is given the said initial registers that powers on the startup value after starting according to enabled instruction.
6. method according to claim 3 is characterized in that, said entry condition comprises: when the initial registers that powers on of said house dog is not endowed masking value, start said house dog.
7. the watchdog system in the embedded device comprises: counter, the initial registers that powers on, powering on of being connected with said embedded device are confirmed code registers and are started code registers; It is characterized in that, also comprise:
Differentiate logic module, be used for value in the said initial registers that powers on and be initial value and the value of confirming code registers of powering on when confirming coding, shield said counter and compose masking value for the said initial registers that powers on for preset powering on.
8. system according to claim 7; It is characterized in that; Also comprise:, be used for level signal with a predetermined period and trigger said differentiation logic module and confirm that from said powering on code registers reads coding with the last power detection circuit that said differentiation logic module is connected.
9. system according to claim 7 is characterized in that, when the value that said differentiation logic module is composed masking value and said startup code registers in the said initial registers that powers on is the startup coding of presetting, starts said counter.
10. system according to claim 7 is characterized in that, said differentiation logic module directly starts said counter when the said initial registers that powers on is not composed masking value.
11. system according to claim 7 is characterized in that, also comprises: be connected in said embedded device and power on and confirm code registers and start the serial-parallel conversion circuit between the code registers.
12. system according to claim 11 is characterized in that, also comprises: the frequency division that is connected between said serial-parallel conversion circuit and the counter is provided with register, is used for storing the trigger interval cycle of said watchdog system.
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| CN101751303B true CN101751303B (en) | 2012-09-19 |
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| CN102622278B (en) * | 2012-03-07 | 2014-03-05 | 北京经纬恒润科技有限公司 | Watchdog monitoring circuit and monitoring method |
| CN102637139A (en) * | 2012-04-13 | 2012-08-15 | 华为技术有限公司 | Method, device and single panel for feeding watchdog by embedded system |
| US8943303B2 (en) * | 2012-07-05 | 2015-01-27 | Infineon Technologies Ag | Monitoring circuit with a window watchdog |
| CN104636215B (en) * | 2015-03-13 | 2018-04-20 | 北京经纬恒润科技有限公司 | A kind of hardware watchdog and its application circuit |
| US9612893B2 (en) * | 2015-05-11 | 2017-04-04 | Silicon Laboratories Inc. | Peripheral watchdog timer |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1632760A (en) * | 2003-12-24 | 2005-06-29 | 华为技术有限公司 | Method for preserving abnormal state information of control system |
| CN2888533Y (en) * | 2006-02-20 | 2007-04-11 | 深圳迈瑞生物医疗电子股份有限公司 | Circuit module against fault resetting of SCM |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1632760A (en) * | 2003-12-24 | 2005-06-29 | 华为技术有限公司 | Method for preserving abnormal state information of control system |
| CN2888533Y (en) * | 2006-02-20 | 2007-04-11 | 深圳迈瑞生物医疗电子股份有限公司 | Circuit module against fault resetting of SCM |
Non-Patent Citations (1)
| Title |
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| JP平11-342736A 1999.12.14 |
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