Later, we were running out of space in flash (252 KB used out of 256 KB with still more features to be added), so my boss had me do a comparison of various compilers to see if there were any that would give us a smaller code footprint. Since I had previous experience with IAR, I suggested that my company choose them, which we did. MOV TH1, #01H sets the value of 01H in the lower bit of timer 1īACK: JNB TF1, BACK checks the TF1 flag in TCON register continuously to know if overflow has occurred or notĬLR TR1 clears TR1 flag to stop the timerĬLR TF1 clears overflow bit as the timer is resetĭJNZ R3, AGAIN keeps looping the statements after again keyword till the value in R3 reduces to 0.A few years back we transitioned from 8051 assembler to 32-bit ARM processors. MOV R3, #200H used as a counter to create a delay of 14 secondsĪGAIN : MOVTL1, #08H sets the value of 08H in the lower bit of timer 1 and the again keyword helps to create a loop. This instruction clears the carry flag as well 3 bytes 24 clock cycles Unaffected Unaffected Unaffected Example MOV TMOD, #10H The value 10H is 00010000B and selects mode 1 of timer 1 3 bytes 24 clock cycles Unaffected Unaffected Unaffected JBC Address, Address This instruction transfers the control to the destination address if the source address has the bit 1.

3 bytes 24 clock cycles Unaffected Unaffected Unaffected JB Address, Address This instruction transfers the control to the destination address if the source address has the bit 1. 2 bytes 24 clock cycles Unaffected Unaffected Unaffected JNB Address, Address This instruction transfers the control to the destination address if the source address has the bit 0.

2 bytes 24 clock cycles Unaffected Unaffected Unaffected JNC Address/label This instruction transfers the control to the specified address/label if the carry flag has the value 0. Execution Time Flags affected Carry Overflow Auxilary carry JC Address/label This instruction transfers the control to the specified address/label if the carry flag has the value 1.

Iar 8051 memory limit