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projects:icspio [2014/12/23 18:18] 127.0.0.1 external edit |
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| - | ==== ICSP I/O ==== | ||
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| - | ICSP I/O is a protocol and group of functions designed | ||
| - | to quickly develop test code for the devices supported | ||
| - | by the k8048 Microchip PIC programmer. | ||
| - | |||
| - | It uses the I/O lines used by the ICSP programming | ||
| - | protocol and is compatible with bit-bang programmers such as | ||
| - | the Velleman K8048. | ||
| - | |||
| - | ICSP I/O was not designed a replacement for more established | ||
| - | and more reliable protocols but it can be used for prototyping. | ||
| - | |||
| - | ==== Usage==== | ||
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| - | < | ||
| - | # | ||
| - | # | ||
| - | # | ||
| - | # | ||
| - | # | ||
| - | NPINS | ||
| - | # | ||
| - | </ | ||
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| - | Internal variable addresses are assigned at the current CBLOCK address. It is up to | ||
| - | the main source file to ensure that this address is both valid and that there is enough space for allocation. | ||
| - | |||
| - | ==== Demo ==== | ||
| - | |||
| - | == Set LEDs and read switches in a loop == | ||
| - | < | ||
| - | ktest 5 ARG | ||
| - | </ | ||
| - | |||
| - | == Set LEDs and read switches from the command line == | ||
| - | < | ||
| - | kio CMD ARG | ||
| - | Src/ | ||
| - | Src/ | ||
| - | </ | ||
| - | |||
| - | ==== Functions ===== | ||
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| - | == GETBYTE == | ||
| - | Fetches a byte from the master (host) and stores it in BUFFER.\\ | ||
| - | Sets W and also sets the carry bit on error (time-out, protocol or | ||
| - | parity error). | ||
| - | |||
| - | == SENDBYTE == | ||
| - | Sends a byte in W to the master (host).\\ | ||
| - | Sets W and also sets the carry bit on a time-out error. | ||
| - | |||
| - | == SENDACK == | ||
| - | Calls SENDBYTE with W=ACK (acknowledge) | ||
| - | |||
| - | == SENDNAK == | ||
| - | Calls SENDBYTE with W=NAK (negative acknowledge) | ||
| - | |||
| - | 2 levels of stack are used when calling the routines GETBYTE, SENDBYTE or | ||
| - | SENDTERM. On 12-bit word architecture devices do not call any of these | ||
| - | routines from within a sub-routine since it will overflow the stack. | ||
| - | |||
| - | ==== Protocol ===== | ||
| - | |||
| - | PGD is used for data I/O with even parity and PGC for clock synchronisation. | ||
| - | PGC is unidirectional and is only controlled by the master (host), this is the | ||
| - | slave. The interface may or not be inverted but this is catered for by the | ||
| - | k8048 Microchip PIC programmer BITRULES inversion logic. | ||
| - | |||
| - | Data is setup on the master prior to a clock low to high transition and setup | ||
| - | on the slave after a clock low to high transition. Data is read after a clock | ||
| - | high to low transition on both master and slave. | ||
| - | |||
| - | Start and stop bits have data held low and high respectively and if invalid | ||
| - | then a protocol error is flagged and the transaction terminated without further | ||
| - | communication on either end. Parity error causes a similar closure of the | ||
| - | session. | ||
| - | |||
| - | < | ||
| - | | ||
| - | | ||
| - | | ||
| - | | ||
| - | | ||
| - | | ||
| - | </ | ||
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| - | 1 start bit, 8 data bits, even parity and one stop bit. The data line is | ||
| - | normally held high since in order to operate bi-directionally data output must | ||
| - | be held high in order for data input to operate with the Velleman K8048. | ||
| - | |||
| - | ==== Reference ==== | ||
| - | |||
| - | ^Arch. ^Stack level| | ||
| - | | 12 | 2 | | ||
| - | | 14 | 8 | | ||
| - | | 16 | 31 | | ||
| - | |||
