The static discharge firmware and the software principle of design in deals with the static discharge aspect, besides the well known hardware method, the firmware and software also is playing the vital role.
Although the firmware design cannot prevent in the system the component damage, but can effectively avoid some non- permanent damage. Through firmware which suitably reads in, cannot be restored the equipment failure (deadbolt lock) usually may avoid, may restore the breakdown also may reduce 10 times.
Is similar to on the hardware the static discharge measure to be same, the anti- static discharge firmware also has the price. Usually, the procedure can bigger somewhat, this mean need longer programming time and memory cell. When measures the success and failure, must does this kind of price and time the pure dependence hardware solution static discharge question cost the contrast. In in many microprocessors applications, the firmware measure cost must be lower than the hardware.
When compilation static discharge 抗扰�?strong firmware certainly must set up an idea is "not the determinism". Also is, certainly cannot think the port, the register and so on the condition is certain. For example, when uses an index register, should ask, if this index has time the mistake, can have any question. If only only has some temporary or the immaterial question, if the light emitter diode glitters, then does not need any special processing. If can have very serious issue, for example phylogeny deadbolt lock, then must take the measure to avoid the question the occurrence.
The firmware (software) the static discharge measure may divide into two kinds:
* Renovates
* The examination and rereads in
Under discusses each kind of measure from the concept, and produces some examples. Because is impossible to foresee all peculiar circumstances, must enable the firmware to resist the static discharge, designs the personnel to have to have a comprehensive understanding to the overall system. Although the under discussion mainly aims at the firmware, but many concepts regarding the software design also are suitable.
Renovates:
Carries on when renovates, programmer not nice past situation, but only will be guarantees the next condition with the determination data. For example, when reads the fetching from 8,409 ports according to, certainly must first to the port read in the data. Even if this port has not later rewritten from an on renewal, also must carry on this step. Do not think on the port also is retaining the data which on time reads in. Renovates when needs to consider other factors include:
A) opens the severance according to the certain time-gap to enable the end (in 8049 is RETR, in 8051 is RETI)
B) when the port uses in the serial data output, renovates stops the position the level.
C) renovates the latch and the port output condition.
D) regularly reads takes the control and the choice input, the guarantee system work in the suitable condition.
E) regarding 8,049 and 8,051 processors, in each procedure ring circuit at least has a register select order.

When carries on renovates, another needs to consider the factor is an order which renovates. Sometimes, renovates the order is extremely important. For example, in the lock input/output, the data line certainly must in front of the clock line renovates. Otherwise, the process renovates the clock can cause the data position loss. 如前所��, certainly must consider under the wrong condition each instruction order.
Examination and replacement:
Sometimes, purely renovates or insufficiently. In some situations, renovates even can cover some serious issue. In these situations, the register, the port and so on need to confirm its condition through the examination. If the condition is not right, the procedure should attempt to it to carry on the correction.
Carries on the replacement (or initialization) when certainly must be extremely discrete. Although the system condition possibly has the question, but the system thorough initialization certainly is not a good method. This could lose all past the data. Should observe the principle is, causes the system to be at the most possible condition, but this condition should cause the question the harm to be smallest. If some keys project not most possible condition, then should retain its condition. This will be advantageous for later to use the voting the way to determine the current condition. Usually, "3 takes 2" the voting way was allowed.
The examination function usually may divide into 3 kinds. Below specially must do examines, if the discovery mistake, needs to initialize.
A) the test routine flows whether correct:
Front 1) in the master routine, returns in the subroutine, wants the periodic inspection subroutine storehouse indicator, confirmed the subroutine in prearranges in the scope moves.
2) if does not inspect the storehouse indicator (or in inspection storehouse indicator foundation), may use "the product label" to help in the discovery procedure movement the question. When enters a sub- procedure, preserves the product label, when leaves the subroutine, inspects this product label.
3) in is durable in the region to arrange "the trap" the code, for example code table or useless severance vector. When the procedure needs to carry out these yards, is held (for example has not arranged in use form bridging order).
For the inspection routine below flows whether normally, also should contain two stature procedures in the procedure:
4) in order to confirm the master routine movement is normal, should have the time procedure which never can stop and expire.
5) the master routine should above the regular inspection fixed time the procedure, confirm whether it does move normally (outside if the microprocessor in has not set the timer, may use the hardware which sets "看门�? the electric circuit. When the processor not on time repositions the timer, outside sets at the electric circuit to be able to reposition the processor).

B) examines the data and the information which saves are whether correct
1) regularly carries on the vote to the retention project, if does not have the uniformity, carries on the initialization. Specially, the condition symbolized (specially is enables sign) to have to retain has the backup. Besides backup, but also may use the error correcting code.
2) regarding the index and other some extremely important register, in uses in front of the data which its saves, must to its value or the scope advanced line of inspection.
3) if the essential data are very many but does not suit the backup, or is unable when examines all information, may use the examination and or the periodic redundant check (CRC) comes to the block data examination.

C) to inputs carries on the examination with the output
1) uses each method, like the parity check, the examination and so on, to input carries on the examination
2) confirmed the data-in the rationality, some data possibly have the obvious mistake.
3) at least takes a sample to all inputs level level two time to realize to the noise "the software filter"
4) through causes the receiver response output stage to carry on verifies the out-port
5) the receiving device ought to be able to distinguish all effective input signal, if the receiving device cannot distinguish, then the transmitter installation should have the again through-put capacity.
If above the measure cannot correctly inspect, then requests to be able the self-recovery. Certainly, this kind restores the ability usually not to be able with to add the electricity (or hardware) repositions in the process the initialization routine to be different, RAM should not clear remove. In fact, when (ESD) causes the wrong procedure reverse replacement as a result of the static discharge, carries out the hardware initialization routine not to be supposed to hinder the processor the work. This usually may reposition the procedure through the inspection execution hardware the symbol register priority to complete. If already established the symbol, then should avoid completely repositioning. When master routine execution, this sign reis established, generally only is repositioned by the processor actual hardware eliminates. Specially, usually should complete the replacement according to the below step:
1st, replacement subroutine storehouse indicator.
2nd, repositions the FIFO indicator.
3rd, reset counter.
4th, prevents the suspicious code the transmission.
5th, completes when the replacement only then permits the severance, then restarts the counter again.
6th, replacement severance indefinite symbol
7th, renovates the output.
8th, if the main engine system accepts the replacement, an easiest to use its round pound code informs the replacement to complete. Then, the main engine may take the measure all to guarantee the system partial all to harmonize identically works.
9th, certainly, the replacement procedure must eliminate causes the replacement movement concrete question.

The above majority of discussions suppose the system to be at the executive routine in the condition (although is not necessarily correct), ` if the procedure includes the form, the processor possibly can carry out these unit values with every effort and take it as the instruction. Theoretically speaking, the memory unit value possibly can cause 看门�?the counter to stop counting, thus causes the processor to enter the endless loop. Regarding this kind of situation, may receive the logical analyzer the address bus, like this has the possibility to find the question the crux to be at. A circulation period memory unit value should replace by a bridging order. This generally can cause the processor to jump out the circulation, thereupon the procedure possibly can change, therefore, is replaced the unit value then passed through the special way to carry on processing. (If has the possibility, the idle memory unit address applies to controls this to return to the operation code. In fact, if front place states, fills up the return code all idle addresses is extremely has the possibility.) Certainly, this logical analyzer also can discover the procedure other parts of endless loop. However, if uses has 伪程�?the monolithic microprocessor to carry on the design, then the address bus will change invalid. In this kind of situation, after the debugging, the procedure may has "the static discharge reinforcement" in the simulation system the nature. Once the procedure is debugged good also the movement normal speech, it may change the register the value to simulate the static discharge effect at will.
The program counter is very essential, should establish at will the value. Moreover, the subroutine storehouse indicator should establish the variable value. Through makes these changes in the simulation process also does not affect the result, many latent questions all may be able to discover. This method certainly not always effective, but has the special question the system is does not permit. Using these principles, with the firmware correlation static discharge question on the other hand can very few.