1) I’ve updated my resume for those of you who care about such things. It’s at http:\/\/www.sheer.us\/resume\/SheerResume-ascii-wa.txt<\/p>\n
2) Below please find a bootloader for a Atmel AVR AtMega8 which accepts a binhex file uploaded via windows terminal (or however else you would like). I’m releasing this code to the public domain at this point. Feel free to do whatever you like with it, or not, as appropriate. It could probably easily be modified for any AVR CPU<\/p>\n
start_bld:
\n\tcli
\n\tldi ZL, LOW(RAMEND)
\n\tldi ZH, HIGH(RAMEND)
\n\tout SPL, ZL
\n\tout SPH, ZH\t\t; set up the stack<\/p>\n
\trcall init_bld\t\t; set up some hardware stuff
\n\trcall idle_timer2_bld\t; start timer2 ticking
\n\trcall set_system_clock_bld\t; setup the system clock for 7.2738Mhz<\/p>\n
\t; check and see if there is a serial console present<\/p>\n
\tsbis RS232_INVALID_IN_PORT, RS232_INVALID
\n\trjmp bld_do_boot\t\t\t\t; if no console, boot<\/p>\n
\tldi uart_char, XON\t\t\t; send welcome banner
\n\trcall uart_put_char_bld
\n\tldi uart_char, ‘B’
\n\trcall uart_put_char_bld
\n\tldi uart_char, ‘l’
\n\trcall uart_put_char_bld
\n\tldi uart_char, ‘d’
\n\trcall uart_put_char_bld
\n\tldi uart_char, ‘>’
\n\trcall uart_put_char_bld<\/p>\n
\trcall uart_get_char_bld_to\t; get a char, or timeout and fall through
\n\tbrts bld_do_boot
\n\tcpi uart_char, ‘B’\t\t; if ‘B’, then boot right now
\n\tbreq bld_do_boot
\n\tcpi uart_char, ‘U’\t\t; if ‘U’, then go into upload mode
\n\tbreq bld_do_upload\t\t; todo: authentication<\/p>\n
bld_do_boot:
\n\tjmp ivec_reset<\/p>\n
; ‘stubbies’ used to make short relative jumps work okay<\/p>\n
bld_do_upload_crc_special1:
\n\trjmp bld_do_upload_crc_special<\/p>\n
bld_do_flush1:
\n\trcall bld_do_flush
\n\trjmp bld_do_upload<\/p>\n
bld_do_upload_err1:
\n\trjmp bld_do_upload_err<\/p>\n
; ******* Upload routine. Decodes lines of Intel Hex, writes them to the flash
\n; displays a error for bad lines<\/p>\n
bld_do_booty:
\n\t\trcall bld_do_flush
\n\t\trjmp bld_do_boot<\/p>\n
bld_do_upload:
\n\t; for now, fetch a line, check its checksum, report back good or bad, wash, rinse, repeat
\n\trcall crlf_bld
\n\tldi ZL, LOW(STRING_SCRATCH)
\n\tldi ZH, HIGH(STRING_SCRATCH)<\/p>\n
\trcall uart_get_string_bld
\n\tldi uart_char, XOFF\t\t\t; send XOFF in case this
\n\trcall uart_put_char_t_bld\t\t; takes a while
\n\trcall crlf_bld\t\t\t; debugging
\n\tldi ZL, LOW(STRING_SCRATCH)
\n\tldi ZH, HIGH(STRING_SCRATCH)<\/p>\n
\tclr XL
\n\tclr sample_cnt<\/p>\n
\tld uart_char, Z
\n\tcpi uart_char, ‘:’
\n\tbreq bld_do_upload_ok
\n\tcpi uart_char, ‘F’
\n\tbreq bld_do_flush1
\n\tcpi uart_char, ‘B’
\n\tbreq bld_do_booty
\n\tcpi uart_char, CR
\n\tbreq bld_do_upload
\n\tcpi uart_char, LF
\n\tbreq bld_do_upload
\n\trjmp bld_do_upload_err1
\nbld_do_upload_ok:
\n\trcall ascii_to_bin_hex_bld\t; convert first 4 bytes of input
\n\t\t\t\t\t; (should be length and high addr)<\/p>\n
\tsts LINE_LEN, TempH\t\t; save length in RAM
\n\tmov Temp2, TempH\t\t; store byte count in temp register<\/p>\n
\tsub XL, TempH
\n\tsub XL, Temp\t\t\t; compute checksum<\/p>\n
\tsts LINE_ADDR_H, Temp\t\t; store high byte of address<\/p>\n
\trcall ascii_to_bin_hex_bld\t; convert second 4 bytes of input<\/p>\n
\tsts LINE_ADDR_L, TempH\t\t; store low byte of address
\n\tsts LINE_TYPE, Temp\t\t; store line type<\/p>\n
\tsub XL, TempH\t\t\t; compute checksum
\n\tsub XL, Temp<\/p>\n
\t; fetch data, store in line<\/p>\n
\t; hopefully data is even, but no guarentee<\/p>\n
\tldi YL, LOW(LINE)
\n\tldi YH, HIGH(LINE)<\/p>\n
\tcpi Temp2, 0
\n\tbreq bld_do_upload\t\t; if zero length record, skip<\/p>\n
\tdec Temp2\t\t\t; LENGTH is +1, from dec standpoint<\/p>\n
bld_do_upload_loop:
\n\trcall ascii_to_bin_hex_bld\t\t; translate ascii to binary<\/p>\n
\tst Y+, TempH\t\t\t\t; store bytes (high)
\n\tst Y+, Temp\t\t\t\t; store bytes
\n\tsub XL, TempH\t\t\t\t; compute checksum
\n\tsub XL, Temp<\/p>\n
\tdec Temp2\t\t\t\t; LEN was given in bytes
\n\tbreq bld_do_upload_crc_special1\t\t; special case: odd number of bytes
\n\tdec Temp2\t\t\t\t; but we do words so need 2 decs
\n\tbrne bld_do_upload_loop\t\t\t; go around again?<\/p>\n
\trcall ascii_to_bin_hex_bld\t\t; grab CRC
\n\tsts LINE_CHECK, Temp\t\t\t; store CRC
\nbld_do_crc_check:<\/p>\n
\tlds TempH, LINE_TYPE<\/p>\n
;\tldi uart_char, ‘0’
\n;\tadd uart_char, TempH
\n;\trcall uart_put_char_bld<\/p>\n
\tcpi TempH, LINETYPE_HDR
\n\tbreq bld_do_upload<\/p>\n
\tcp Temp, XL\t\t\t\t; compare CRC to stored
\n\tbrne bld_do_upload_err1\t\t\t; if it doesnt’ match, err<\/p>\n
\t\t\t\t\t\t; matches, so program part<\/p>\n
\tldi YL, LOW(LINE)\t\t\t; use Y ptr to access
\n\tldi YH, HIGH(LINE)\t\t\t; stored data for this line
\n\tlds Temp2, LINE_LEN\t\t\t; Temp3 contains countdown
\n\tlds ZL, LINE_ADDR_L\t\t\t; Z ptr is address in flash
\n\tlds ZH, LINE_ADDR_H
\n\tldi XL, LOW(BOOTLOAD_START*2)\t\t; X ptr is max flash addr to write
\n\tldi XH, HIGH(BOOTLOAD_START*2)\t\t; keeps us from writing bootloader
\n\t\t\t\t\t\t; which would put is in NWRW state
\n\t\t\t\t\t\t; and be bad<\/p>\n
bld_do_program_loop:
\n\tcp XL, ZL\t\t\t\t; check to see if we’re
\n\tcpc XH, ZH\t\t\t\t; outside of the bootloader
\n\tbrlo bld_do_program_loop_end\t\t\t; do not program bootloader
\n\t\t\t\t\t\t; even if it is in file
\n\tmov TempH, ZH\t\t\t\t; grab the page
\n\tmov Temp, ZL\t\t\t\t;
\n\tandi Temp, 0xC0\t\t\t\t; skip off the byte address
\n\t\t\t\t\t\t; leaving only the page address<\/p>\n
\tlds Temp3, LAST_PAGE_L\t\t\t; compare against
\n\tcp Temp, Temp3\t\t\t\t; the last page that
\n\tlds Temp3, LAST_PAGE_H\t\t\t; we used and
\n\tcpc TempH, Temp3\t\t\t; if it’s different
\n\tbreq bld_do_program_skip_write\t\t; then we need to write that page<\/p>\n
\t\t\t\t\t\t; if we get here, then we must
\n\tpush ZL\t\t\t\t\t; preserve Z
\n\tpush ZH<\/p>\n
\tlds ZL, LAST_PAGE_L\t\t\t; restore previous Z (page we
\n\tlds ZH, LAST_PAGE_H\t\t\t; want to write)<\/p>\n
\trcall wait_spm_bld\t\t\t; wait for SPM to clear<\/p>\n
\tldi Temp, (1< ascii_to_bin_hex_cont_bld:<\/p>\n \tadiw ZH:ZL, 1 \tldi mc16uL, 16\t; load 16 \trcall mpy16u_bld\t; and multiply<\/p>\n \tadd m16u0, XH\t; Add current value to stack \tmovw YH:YL, m16u1:m16u0<\/p>\n \tdec XL\t\t\t; This keeps us from ascii_to_bin_hex_end_bld: uart_put_string_bld: uart_put_string_loop_bld: uart_put_string_done_bld: crlf_bld: uart_put_char_t_bld: \tpush Temp 1) I’ve updated my resume for those of you who care about such things. It’s at http:\/\/www.sheer.us\/resume\/SheerResume-ascii-wa.txt 2) Below please find a bootloader for a Atmel AVR AtMega8 which accepts a binhex file uploaded via windows terminal (or however else you would like). I’m releasing this code to the public domain at this point. Feel […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[],"_links":{"self":[{"href":"https:\/\/www.sheer.us\/weblogs\/wp-json\/wp\/v2\/posts\/1604"}],"collection":[{"href":"https:\/\/www.sheer.us\/weblogs\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.sheer.us\/weblogs\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.sheer.us\/weblogs\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.sheer.us\/weblogs\/wp-json\/wp\/v2\/comments?post=1604"}],"version-history":[{"count":2,"href":"https:\/\/www.sheer.us\/weblogs\/wp-json\/wp\/v2\/posts\/1604\/revisions"}],"predecessor-version":[{"id":4091,"href":"https:\/\/www.sheer.us\/weblogs\/wp-json\/wp\/v2\/posts\/1604\/revisions\/4091"}],"wp:attachment":[{"href":"https:\/\/www.sheer.us\/weblogs\/wp-json\/wp\/v2\/media?parent=1604"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.sheer.us\/weblogs\/wp-json\/wp\/v2\/categories?post=1604"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.sheer.us\/weblogs\/wp-json\/wp\/v2\/tags?post=1604"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
\n\tmovw mp16uH:mp16uL, YH:YL<\/p>\n
\n\tclr mc16uh\t; into multiplier<\/p>\n
\n\tclr XH
\n\tadc m16u1, XH\t; carry as needed<\/p>\n
\n\tbrne ascii_to_bin_hex_loop_bld<\/p>\n
\n\tmovw TempH:Temp, YH:YL
\n\tpop YH
\n\tpop YL
\n\tpop Temp2
\n\tpop XL
\n\tpop XH
\n\tret<\/p>\n
\n\t; put a null-terminated string to the uart
\n\t; Z should be pointing to the beginning of the string in RAM
\n\tclr uart_char
\n\tst Z, uart_char
\n\tldi ZL, LOW(STRING_SCRATCH)
\n\tldi ZH, HIGH(STRING_SCRATCH)<\/p>\n
\n\tld uart_char, Z+
\n\tcpi uart_char, 0
\n\tbreq uart_put_string_done_bld
\n\trcall uart_put_char_bld
\n\trjmp uart_put_string_loop_bld<\/p>\n
\n\tret<\/p>\n
\n\tldi uart_char, CR
\n\trcall uart_put_char_bld
\n\tldi uart_char, LF
\n\trcall uart_put_char_bld
\n\tret<\/p>\n
\n\tsbis RS232_INVALID_IN_PORT, RS232_INVALID
\n\trjmp uart_put_char_t_done_bld<\/p>\n
\n\tin Temp, UCSRA
\n\tsbr Temp, (1<